The first time I saw Greenday in 1994, they had the audience decide between two guys to play one song. When I saw them again after they became the major band of the era, they did the same thing but a little different. Still one of the fans got to get on stage, play BJ's guitar and for sure a wonderful moment.

All that said, considering the way punks think, this is probably just the most recent shenanigans. I am willing to bet that someone started to play Freebird long before someone attempted to sneak in Wonderwall

Would actually be funny if someone were to try and play some of the George Harrison Wonderwall