Trivia: Just after Lucas tells Joe he's a 'superb manager', Joe drags him off to beat him up in his office. When he takes him into the back, you see a girl standing in the doorway. She is the same girl you see when Mark and AJ enter the store at the beginning. Her character was called Lily and she was cut out of the film. Her name is also still in the credits.
Trivia: "The autograph" girl, is Kessia Randall, the real-life sister of Ethan Embry (Mark).
Trivia: Ethan Embry's (Mark) brother, Aaron, is also in the film, as an uncredited mosh-pitter.
Answer: I'm pretty sure it was the Eddie that gave him the brownies, because the band we see that is onstage at the time is Gwar, if I am not mistaken. They were famous for having a monster onstage that would 'eat' fans.
T Poston
Yeah, cause Eddie gave him the pot brownies that made him hallucinate being in a Gwar show, so he's thanking him.