Plot

The night before his big medical school interview, a promising student celebrates his 21st birthday with his two best friends.

When Straight-A college student Jeff Chang's two best friends take him out for his 21st birthday on the night before an important medical school interview, what was supposed to be a quick beer becomes a night of humiliation, over indulgence and utter debauchery.—Relativity

It's Jeff Chang's 21st birthday, so his friends, Miller and Casey show up to help him celebrate. But Jeff has an interview the next day for medical school which his very strict father is going to bring him to, so he can't go out. But Miller convinces Jeff to go out and they get so drunk that they don't know where they are and how to get back Jeff's place. So they try to ask a girl whom Jeff knows if she could help them but she doesn't know either. But she tells them maybe her boyfriend might know. So they go to him but problem is that the guy is someone they met during their binge and all he wants to do is kill them so they run off. And they try to find Jeff's place before his father shows up and kills them.—rcs0411@yahoo.com

College seniors and lifelong friends Miller (Miles Teller), a fast-talking hedonist, and Casey (Skyler Astin), a nice guy and soon to be stockbroker, arrive at the college where their third BFF Jeff (Justin Chon) is a medical student. It's Jeff's 21st birthday and Miller is desperate to get his buddy blindingly drunk, and enjoy one last amazing night before they all start their adult lives. Jeff protests because his demanding father has orchestrated and important job interview in the morning, but soon enough the birthday boy relents and eventually gets so thoroughly hammered he can barely speak, which presents a problem when Miller and Casey can't remember where there buddy lives. The trio sets off one wild adventure to find anyone on campus who can tell them where Jeff lives so that they can get him ready for his big appointment..

Jeff, Casey and Miller have been best friends in high school. Casey and Miller, themselves already 21 or over, want to take Jeff out for his 21st birthday. However, it is on the night before an important medical school interview, so he declines. After Miller threatens to make a lot of noise the whole night if he persists in his refusal, he accepts to come along for just one drink.

In a bar Jeff accidentally hits a boy named Randy with a dart. Randy gets aggressive and they have to flee, even though Casey was having a nice chat with a girl named Nicole. Jeff gets excited that he is allowed to enter bars now, drinks too much and gets unresponsive. Casey and Miller want to take him home, but do not remember where he lives. Since Nicole knows Jeff, they try to find her, because she may know where he lives. They sneak into a sorority house, where they think Nicole lives, but it is the wrong house, where only female Latina students live. They encounter two blindfolded women ready to be paddled as part of their sorority initiation ritual, but these and the other women of the house are furious when they find out about the intrusion. They have to flee the house, and Casey and Miller throw Jeff from a balcony onto the pool cover that bounces him into a rose garden, and worry that they killed him, but he is not injured, except for thorns in his buttocks.

They find Nicole, but she does not know the address, and refer them to Randy, who turns out to be her boyfriend. After Randy refuses to look up the address in his telephone, Miller threatens him with the gun they found in Jeff's pocket, to steal the telephone. He shoots into the air, causing a buffalo to panic and attack people, including Randy. At the address they find, it turns out that he does not live there anymore. There is a party going on in the house, and they have to join games in order to get access to the boy who may know the address. Finally, they have access to him, but he does not know the new address. Through the movie Miller & Casey find from the folks they meet about a dark side of Jeff's past. They find a gun on him, find that he was arrested for attempted murder & is considered by people at large to be a nutcase.

They leave Jeff in the care of two stoned students, who for fun undress him and glue a teddy bear to his penis. After leaving the party he goes out on the street still like this. Casey and Miller want to get him dressed, but he runs away and is arrested. Casey and Miller go to the police station, where they are told he has been transferred to a mental hospital. A woman pretends to escort them to that place, but it is a trap by the Latino women. They take revenge, and Casey and Miller, with buttocks branded and bruised by spanking, have to walk on the campus dressed in nothing but socks on their penises to get new clothes. On the way Casey is angry at Miller as he thinks Miller's lack of responsibility caused the entire incident in the first place.

In the mental health facility, Casey and Miller want to take Jeff home, but the hospital refuses. In his hospital file, they find that Jeff attempted suicide with a gun, which misfired & hence was arrested for attempted murder. Then they smuggle him out, for which they have to throw him from the third floor, making them worry that they "killed him again", but again he is not injured. Jeff, now awake, steals the car on which he was dropped which turns out to be Randy's, and they flee, with Jeff driving recklessly. They find Jeff's real address on his hospital file.

Finally, Casey and Miller help Jeff to get ready for the interview. They pull the teddy bear off, circumcising Jeff in the process, and dress him well. Jeff tells Casey & Miller that he was simply stressed out of his mind & he is not suicidal. Randy has arrived at Jeff's home to destroy the room, but his father hits him. Encouraged by Casey and Miller, Jeff confesses to his father, who pressured him to go to medical school, that he does not want this. The father does not accept this, until Miller hits him. Randy admires Jeff for standing up against his father and reconciles with him.

Miller, who is intelligent but has had poor marks due to not working hard, improves, and wants to go to university. The night before an interview he is at a music festival with Casey, Nicole, who is Casey's girlfriend now, and Jeff. He has a wild night and arrives at his professor with a broken leg and red hair. It turns out to be the odd man he has seen dancing alone in the street all the time in that earlier night.