If you offer Goober a cig as he's leaving the clinic after a performance, the game can freeze (he's already out the door while Kathy's trying to talk to him).

Possibly other items to I guess, but that's the only one I tried it with before figuring out the puzzle, so make sure he's still in the middle of a performance before using items on him, or have a recent save (autosave bailed me out here as I hadn't saved in a while).

Cool. Had a lot of fun with this game, hope there's a sequel. :)