I've had some hilarious conversations with cops while high out of my mind. When you're in a massive crowd of people on high corn chips as long as you aren't a total douche the cops usually just get a kick out of your idiocy.
my friends that went to Coachella last year were detained for having illegal tickets at the gate (totally didn't have illegal tickets, just looked like shady fucks), and they kept them for four hours, made my friend cry, trying to scare them into admitting they faked the tickets or bought from scalpers. Eventually they let my friends in. And supposedly 15,000 people snuck in last year. Talk about wasted resources.