Brian: You don't need to put your P in a V right now.
Peter Bretter: No, I need to B my L on someone's T's.
When the guy walks in on Peter naked in bed, the sheet protecting Peter's modesty is covering him in one frame, and the next moment it has vanished completely.
Some details are taken from Jason Segel's life. For example, the naked breakup is based on a similar incident and he was working on a puppet-based Dracula rock-opera.