The band Twenty One Pilots put on a show at Manchester's AO Arena and ended it with their song Trees, where they drag their drums into the audience, pour water over them, and splash over the crowd while confetti cannons go off around them.
"After the gig, someone was just walking through the arena, holding what’s clearly a customized drum with confetti sticking to it. There’s video of it and everything. People are like, 'I really don’t think you should take that,' but nobody steps in to stop the heist."
The stolen drum was later recovered at the hotel where the thief was staying, thanks in part to fans who flocked to the band's subreddit to track it down. Confirmation of the recovered drum under the cut:
https://instagram.com/p/DJi_U0MCm47

ONTD, have you ever stolen anything at a show?
Sources: 1, 2, 3