NOTE: This spoiler was sent in by travelerbill.
Movie starts out with Mitch, Luke Wilson, leaving two co-workers at a conference of Real Estate lawyers to catch an early flight home. He walks in on his girlfriend Heidi, Juliette Lewis, watching hardcore porn.
He is initially pleased by this until a blindfolded couple comes out of an adjoining room. He discusses her perversion with her in the kitchen until a second dude shows up "for the gangbang."
It immediately shifts to Frank's, Will Ferrell, wedding. One of the groomsmen, Beanie, Vince Vaughn, is encouraging Frank to bail on his fiancée, Marissa Perrey Reeves, right up until the vows. He claims to be tired of his wife, Leah Remini, and kids. At the reception, the best man Mitch gets completely wasted and makes a fool of himself by acting inappropriately toward an old acquaintance, Nicole, Ellen Pompeo. He starts to tell the story of his breakup during the toast but Beanie intervenes and saves the toast and Mitch from further embarrassment. Beanie is obviously a slick smooth talker.
Beanie (with his kids in tow) and Frank help Mitch move into his new house. It is practically on the campus of their old college. Beanie is taken with the idea of throwing a party for Mitch, and Mitch eventually relents. Later Frank tells his new wife that he is going to the party for Mitch. She asks him to take it easy as she doesn't want the reappearance of "Frank the Tank." Apparently his Super Hero alter-ego when he drinks.
The party is HUGE. Apparently Beanie is loaded, owning a bunch of "Speaker City" stores. The house is loaded with an elite sound system, and Beanie has used his influence to get Snoop Dogg to play the party. A bunch of cute girls fawn all over Mitch for obvious reasons. Meanwhile Frank initially rejects, then accepts a funnel of beer, then another and another. Before you know it, he is nude disrupting Snoop Dogg, and exhorting the crown to streak to the quad. Unfortunately, he is the only one that does. Marissa, Lara, and a couple other hot women are in Marissa SUV driving around talking about taking a Blow Job course (remember this). The come upon Frank jogging naked in the street, alone. The show way too much of Franks butt in this movie.
Mitch wakes up with a smoking hot blonde Darcie, Elisha Cuthbert in bed with him, who was only interested in having a one night stand with him. After she leaves he goes downstairs to talk to Beanie. Just in time to have Dean Pritchard, Jeremy Piven, burst in to tell him he's being evicted. The Dean was bullied by the three of them as a kid, and is taking his revenge by claiming the house for University use.
At work Mitch is meeting with his boss. Mitch bungled a real estate deal and is taking it from his boss. As they talk the bosses daughter walks in. Its Darcie, the hot blonde. They act like they've never met as the boss/father tells them how he's so proud of her, and how fast they grow up, and how he can't believe that in seven months she's going to graduate...high school. Mitch chokes on his coffee.
When he gets home Frank is there, he's been kicked out of the house. When they get in Mitch is introduced as "The Godfather" by Beanie who is hosting a rush party trying to get pledges for a non conventional fraternity. Mitch is not enthused, but as Beanie is so slick eventually capitulates.
This leads to a funny sequence of the trio flying around town in a black van picking up the motley crew of pledges. (A giant black dude, a couple other college kids, some middle guys, and an octogenarian named Blue) They then line the pledges on a ledge. Each is holding a cinder block tied to their penis in a trust exercise. Of course it goes wrong for one of the pledges when his cinder block goes through a manhole and he falls to the ground, with out ill effect apparently (a la Wiley Coyote.)
Frank drives around town trying to leave a message for his wife. He keeps erasing and rerecording the message. It cuts to the Blow Job course being taught at Franks old house. Frank shows up and sees the instructor, Andy Dick, in a seemingly compromising position with Marissa due to looking in the wrong window. Andy Dick goes into the kitchen for a drink of water. Frank tries to accost him but is beaten up by the gay BJ instructor.
Mitch and Beanie are putting up the letters on the house when Nicole drops by with a house warming gift with her young daughter. Beanie invites her to his sons birthday party after insulting her gift. Frank comes out with a blow up doll asking for dressing advice.
At Beanie's kiddie party, Beanie is dressed like a clown, and the pledges are all either servants or dressed like cartoon characters. Nicole shows up with her smarmy boyfriend, Craig Kilborne. Frank is dressed in his bathrobe, walking around drunk. Mitch chats with Nicole and they discover a mutual attraction when they were in High School. Mitch walks into the can when Nicoles Boyfriend was mauling a waitress. Kilborne chides Mitch by reminding him of the "Guy Code" of not ratting each other out.
Frank is walking around and finds a tranquilizer gun from the pony ride operator. This is the scene from all the commercials. He walks around all drugged up, smashing through the cake during the song, falling into the pool. He has a dream that he is back with his wife, making out, but he was just making out with the pony ride guy, who was giving CPR. He then kicked him back into the pool.
Later, Mitch is in his office with Nicole having reviewed her lease. She is grateful, kisses him on the cheek and suggests he call her for a date even though she is dating her smarmy boyfriend. At which point two pledges come in looking for "The Godfather" saying they were unable to get as much KY jelly as they were instructed. Mitch reminded them not at work and sent them away. After Nicole and the pledges left, one of the coworkers from the conference pulls Mitch aside and asks to join the fraternity. Mitch feigns ignorance, even when the coworker implies he did the bosses daughter.
The KY was for a co-ed wrestling party Birthday party for Blue at the fraternity. Mitch gets beat by a butch looking woman. And Blue faces off against two topless college ladies. At the sight of them he keels over dead. While this is going on Beanie is in his room with a girl, but he wimps out because he loves his wife and kids.
Franks sings Dust in the Wind at Blues grave site. Afterwards he talks to Marissa about getting back together, but she asks for a divorce.
Nicole and her smarmy boyfriend were looking over the their new apartment when she says that she had Mitch review the lease. The smarmy boyfriend then tells her that he saw Mitch what he was doing to the waitress, breaking the Man's Code. She believes him and when Mitch calls she tells him to get bent. He apparently convinced her to meet because they went to a coffee shop, but the waiter says everything is on the house for "The Godfather." If this wasn't bad enough, Darcie (the one night stand/the bosses daughter) shows up and says that everything was cool, not to worry. At this point Nicole walks out.
Meanwhile Dean Pritchard has bribed the student council president to revoke the fraternity's temporary charter by implying he could get her into Columbia University's Law School. Mitch comes home to the boarded up house and meets the guys at a hotel. He says they are going to fight the dean. He goes to work and sees the coworkers who were at the conference. He tells them they can join the fraternity if they help him out. They are all for it, but his boss walks in saying he better pay attention to the project he's been assigned to. "The Godfather" has taken over Mitch and has everything under control. His boss is impressed.
Turns out they have recourse, they have to pass three tests. A test of their school spirit, academics, and athleticism. Beanie wants to bail, but "The Godfather" guilts him into fighting The Dean. They show up on campus in identical collegiate sweaters and rep ties. They do a dance number for the school spirit, and Frank is in a mascot costume into the flaming ring we've all seen on the commercials. After which the Student Council president confront the dean about his lying to her in the bribe, he dismisses her with a tough luck.
During the academics Beanie speaks into a microphone hidden on him to Mitch's co-workers in a van across the street. They all have receivers in their ear. The athletics portion is chosen by the dean, gymnastics. And he get to choose the participants. He picks Frank to do the floor exercise, he doe the ribbon of rhythmic gymnastics.
He chooses Beanie to do the rings, and he chooses the big fat black dude to do the vault. Of course they all do well.
The dean comes into a room to tell them that they all did well, but since they neglected to remove Blue from their roster their score falls below passing. They are outraged and follow the dean outside. When he calls for security, the Student Council president gives Mitch a tape of the dean confessing. He grabs the recorder and bolts with Frank hot on his tail. They brawl across campus with the Dean beating up Frank in a large classroom, and getting away with the recorder. When Mitch catches up to Frank it turns out that Frank took the cassette out.
The quick wrap up... Nicole comes over while they're all moving out of the house. She dumped the smarmy boyfriend, and she makes up with Mitch. And it is implied that they do it in the Fraternity House. Frank is a DJ at the school and tells everyone that the dean went to jail, and the fraternity got his palatial manor. We see them remove the deans portrait from the above the mantle, replacing it with Mitch. Frank hazes one of Mitch's coworker who are now pledges.
During the credits...
We see Blue sing "Dust in the Wind in heaven.
Frank meets Heidi, Mitch's old girlfriend in the supermarket and she invites him to a swinger party.
Beanie is a soccer coach and way too intense considering he's coaching 6 year olds.
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