What kind of pranks?

Joe: I don't know. There is a mysterious pair of underwear in Glenn's bag when we were on the road, I don't know?! Glenn: It's weird Joe: I don't know Glenn: Things like taking towels on stage, water bottles, "hey, that's my water!" Pete: We get in fights on stage 'cause you know, you're like thirsty, you need water and then you look over and Glenn's got like four of them right by him, you're going 'like hey'! Glenn: Touchy Pete: We're thirsty man