Captain Dickson: You are here because you some Justin Bieber, Miley Cyrus lookin' motherfuckers. You will be going in as undercover high school students.
When Jenko and Schmidt are throwing the house party, Jenko invited the 3 nerds to help him hack Erik's phone. When Jenko lets them in, only two guys walk in, then he shuts the door. In the next shot, all 3 guys are inside.