When their new next-door neighbors turn out to be a sorority even more debaucherous than the fraternity previously living there, Mac and Kelly team with their former enemy, Teddy, to bring the girls down.
The movie opens up with Rose Byrne and Seth Rogen having sex. She spews on him as she finds out she might actually be pregnant.
There is a recurring joke about their daughter Stella finding Kelly’s dildo. The new buyer’s of the house decide to buy their house and they make a joke about how their kid does the same thing but it’s a black dildo.
However, before the new buyers can move in, Mac and Kelly’s house is under escrow, so they have 30 days not to fuck it up or they’re not going to get their house bought.
Jimmy and Mac have lunch, Jimmy is freaking out because his wife, Paula, is having a baby. Jimmy and Mac talk about the differences between girls and boys having sex, it was pretty funny but awkward too. However, I am not a parent, so I laughed heaps.
We meet the characters of Selena Gomez and Chloë Grace Moretz as Shelby, the leader and founder of Kappa Nu, and the president of Phi Lamda, respectively.
Shelby is a new student at the university and the sorority. Shelby is obviously not your typical sorority sister, she is actually anti-sorority when we first meet her. She actually gets in trouble for smoking a joint and is forced to throw it in a cup, much to her displeasure. She is also displeased with the fact that Phi Lamda isn’t allowed to have a sorority party due to the Greek Council rules, only frats are allowed to host parties. However, they are allowed to party, but only at frat parties.
At the first party, Shelby meets a new girl named Beth, a member and co-founder of Kappa Nu. Shelby and Beth go into their first party. They realise it isn’t as fun as they expected it to be. Beth and Shelby, and now Nora – , another member and co-founder of Kappa Nu – decided to leave because the party is boring.
Nora, Beth and Shelby get to know each other with stories and they decide to form their own sorority. Kyle Mooney – Dustin – played their Resident Advisor, he comes into their meeting and finds out that they’re smoking weed. He goes nuts. He seems to have a split personality. Shelby, Nora and Beth get mad, and then decide to start their own sorority.
We finally catch up with Teddy Sanders (Zac Efron), the former president of Delta Psi Beta and the Radners’ enemy-turned-ally – and Pete Regazolli (Dave Franco), the former vice-president of Delta Psi Beta and Teddy’s best friend – Christopher Mintz-Plasse as Scoonie, a former member of Delta Psi Beta, and Jerrod Carmichael as Garf, a former member of Delta Psi Beta – from the first Bad Neighbours and John Early as Darren, Pete’s Boyfriend. They are all having their regular Poker Night, while catching up together.
Darren goes all in on his bet, then he proposes to Pete. Everyone cheers and chant USA! Teddy won’t stop talking about how Pete used to slay much vagina in college. Pete then suggests that Darren move in and Teddy moved out on his own. Teddy is okay with it, but obviously not. Teddy goes for a run to get over his new misery.
Beth, Shelby and Nora get a tour of their new house. It turns out to be the old frat house of Teddy and is friends. The girls find Teddy sitting in one of the rooms. He introduces himself to them. Shelby, Beth and Nora pitch their reasoning for the place to Teddy. Teddy agrees to help them pay for the rent and live there too.
Kelly and Mac walk out of their house and see Teddy with the girls, he rushes the girls and walks over to Kelly and Mac. It’s an awkward encounter as Teddy tells them he now has a criminal record because of them and it is tough to find jobs for him. Mac and Kelly laugh it off but he is serious.
Shelby, Nora, Beth and Teddy make an introduction video to Kappa Nu for YouTube. It is bad. Mac and Kelly come out of their house again and notice a party is happening in the next house. It is their first introduction to the new sorority. Mac and Kelly freak out, even know Shelby, Beth and Nora are really nice. Mac and Kelly ask the girls and their sorority is they could not party for 30 days until the escrow is over, then they can do whatever they like. Shelby tells Mac and Kelly the reason they started the Sorority was because Fraternities are allowed to party whenever they like and Sororities are not allowed to party. Shelby says that Stella would want an outlet to have fun and party just like a guy would, Mac has agrees with it. Teddy reveals to be the mentor behind the sorority, Mac and Kelly are shocked.
Teddy creates a list called ‘Rules for a Successful Sorority’, they are:
1) Use money buckets to keep track of the cash – five buckets a month = house rent.
2) Keep getting pledges and you can dress them up like idiots.
3) Throw type of parties that show them what you guys are all about.
Everyone is dressed up as characters, Teddy and a couple of the girls are dressed up as different versions of Hilary Clinton. The girls and Teddy cry over the movie ‘The Fault in Our Stars’. They do more partying and Mac and Kelly can’t handle it.
Mac and Kelly see the Dean of the University, Dean Carol Gladstone – Lisa Kudrow – to try and get her to close down the house, however, just like in the first movie, it doesn’t work because she can’t do much about it. She claims it would be a PR nightmare ‘Sexist Female Dean Shuts Down Sorority’. Mac and Kelly bribe the Dean, but it doesn’t work. She then tells Mac and Kelly to watch what they say around their daughter because she is going to pick up their swearing. Stella swears, then the Dean makes a joke saying is Stella watching Goodfellas on her iPad. I laughed.
Mac and Kelly decide to call the girl’s parents. Shelby’s dad – Kelsey Grammer – confronts Shelby about starting a sorority when she should be there studying. Shelby’s father decides to let her stay and buy her some new clothes instead. He then tells Kelly and Mac there isn’t much he can do. Shelby, Nora and Beth get in an argument with Mac and Kelly about calling Shelby’s parents.
The next day, a full sorority of girls are sun-baking and drinking on Mac and Kelly’s frontyard. The girls wage more war by throwing bags of wet tampons at their house. Teddy doesn’t fun it as funny. He is actually disgusted by it.
Mac, Kelly, Paula and Jimmy have a brainstorming session on how they can get rid of the girls during the escrow. Mac and Kelly decided to put bed bugs in the girls’ beds.
The new owners come in for their inspection – the house next door is closed down for fumigation – Mac and Kelly say they have new neighbours next door, and it is Paula and Jimmy dressed up as a Jewish couple. Mac makes a joke about Paula being pregnant and having another Jew in the oven. It was funny.
Back at Teddy’s old place, he is putting his stuff in boxes while talking to Darren, Paul and Garf. Teddy screams at Darren. Paul tells Teddy it is weird for him to try and help girls out in a Sorority. He is a grown man! Teddy tells Pete he was never a bro to him, and he leaves.
Shelby tells the girls they need to get more money to pay for their rent after the Fumigation took most of their money. Teddy kind of has a breakdown as he figures out how to help them. Shelby, Nora and Beth text each other trying to figure out what is wrong with Teddy. The girls vote to get rid of Teddy from the house. Teddy freaks out again telling them he quit his job for this and misses out on his 401k, the girls have no idea what that is. Teddy doesn’t know either. The girls thank him for getting them the place, but they don’t need him anymore. The tell him he is an old person and he is no longer needed. Teddy realises he is playing for the wrong team and leaves. Shelby calls the cops about the other houses selling weed.
Mac complains about not being able to get weed from his dealer because he is all dried up. Teddy appears out of no where and tells them we that is. Teddy tells Mac and Kelly he wants to join their side and take down the sorority. He tells them their plan and how they are going to infiltrate the tailgate.
Kelly, Mac, Jimmy, Paula and Teddy arrive at the tailgate in their own college attire, they definitely look out of place. They devise a plan how to steal the weed from the girls.
Teddy gets on stage and dances for all the girls while Mac and Kelly steal the weed from the girls’ table. Shelby sees Mac stealing the weed. Shelby chases after Mac. She catches up with him and steals it back. Jimmy runs off with the weed until he gets his in the face with a massive steak by Miranda. The weed isn’t in Jimmy’s bag. The girls run around Mac again as he has the bag of weed now. Teddy grabs the bag from Mac and runs, Shelby gives chase. Mac and Teddy get in the car and escape.
Mac and Kelly celebrate with sex, and then Mac, Kelly and Teddy burn the weed in a BBQ. Mac and Kelly ask Teddy if he wants to stay with them for the night. He cries over it and thanks them both.
The girls contemplate what they are going to do next. The girls decide to ruin the “old peope’s” lives.
Shelby and Beth break into Kelly and Mac’s house to steal their phones and change their numbers for each other around. Mac is teaching Teddy to boil eggs. He doesn’t get the notion that eggs get hard.
Mac and Teddy get back home and Mac sees a letter from Kelly on the table that says she is leaving him because she is stressing. Mac sends Kelly a message but he doesn’t now it isn’t her number. The text comes back with “NO JOKE. I’M FREAKING OUT ABOUT STUFF. DON’T TRY TO CALL ME.” It’s obviously one of the girls doing it. They trade texts while Mac tries to figure out what is going on. Kelly freaks out about Mac not being there, and she has the same situation with the girls.
Kelly goes to Jimmy’s work and tries to get information out of him as to where Mac is. He actually doesn’t know, but she doesn’t believe him. Kelly calls Mac on Jimmy’s phone and it turns out Mac is in Sydney, Australia, right outside of the Opera House looking for Kelly. They realise they have been pranked by the girls, so Mac says he is going to do the Bridge Walk and then come home.
Kelly and Mac return home to see the girls selling Mac and Kelly’s things. Kelly and Mac argue over who the bad parent is. They compare their experiences with their daughter to see who really is the bad parent. They agree they are both bad parents. Kelly and Mac get a call to meet with the new buyers.
The new buyers don’t want to own the home anymore because they drove by yesterday and say the sorority girls stealing from the house. Mac and Kelly argue with them as to why they didn’t stop them from stealing. Mac pleads with them to see if there is anything they can do by tomorrow.
The girls get an eviction notice from their landlord. Shelby decides that they have to throw a frat party to make the money to pay for their rent, otherwise they have to lose the house. They tell the other girls the plan.
The girls make another invitation video for their new party at the sorority house.
Mac, Kelly, Jimmy, Paula and Teddy decide that they only way they are going to stop the sorority is if they stop this final party from happening.
Jimmy and Teddy get into the party and try to shit it out, Teddy goes upstairs to turn off the power and Jimmy drinks the punch and gets drunk with Nora. Jimmy tells Nora their plan. Teddy reaches the power box and turns it off, but nothing happens as the box isn’t connected to the power supply.
Mac and Kelly go to call the cops but Shelby has the phone. Shelby runs outside with their phones and into their garage and get locked in it by Shelby. Mac and Teddy throw everything they can at the door to try and break it. The items don’t work. Teddy notices an air ducked they can escape through. They break the door instead.
Shelby gets back to the party and the other girls realise the party sucks and they quit the sorority. They leave, Shelby tries to get them to stay. The three girls have a melt down until Kelly tells the girls to stick together and work through it as women! The girls hug it out.
The girls welcome their new additions to Kappa Nu.
Teddy goes back to his old apartment to apologise to Pete. He says he will never lose Pete, they are brothers for life. He says he isn’t losing a best friend, he is gaining a best friend’s husband. Pete asks Teddy is he will be his best man, of course he accepts.
Shelby, Beth and Nora tell Mac and Kelly they want to buy their house. Mac and Kelly agree to do it for five buckets of money a month. The girls and all the new sorority and frat friends party in Mac and Kelly’s house while Mac and Kelly move to their new house.
Kelly and Mac reminisce about what has about over the two movies.
Three months later:
Teddy is helping Pete get dressed for the wedding. Pete is nervous. Teddy tells Pete how much Pete means to him.
The movie ends as Stella gives the new baby girl her first dildo. Mac and Kelly compare dildos with Jimmy and Paula. It was funny.