Ewww. That's nasty.
It really is isn't it? Why would people do that? Apparently it's commonplace at festival type gigs ....................hmmmmmmmmmmmmmmmmm not nice at all IMO,.
I don't know Sooozy. Last gig I went to was a Pat Metheny concert (jingly jangly jazz guitarist) with my dad. To be honest, most of them there looked like they were of an age to have urinary complications but there wasn't a pissy cup to be seen.
Maybe they were wearing their incontinence pads ....................or possibly colostomy bags ..................................................Sorry bad taste!
Maybe it's a protest thing - my daughter said she always stands well back from the front (because of this) and never, ever drinks because the queues for the toilets are ridiculous and that the toilets are really disgusting anyway! I guess if you charge a fortune for tickets and then treat the customers like animals - they'll act like them. Not that i can think of any animal that pisses in a cup and throws it!
Hahaha. My son was born with congenital bladder problems (which caused a whole heap of secondary crisis saga) and he uses a catheter to pee, so I can see the humour in it in theory. But having someone pee over my open toed Gina heels would become a serous issue.
Here's a little Pat to go to bed to. Night 
Sooozy and all.