I thought this would be a fun topic, so here it is. What have you seen Michael, Franklin, and Trevor doing when switching characters?
I've seen Trevor mocking a guy he'd tied to a pole under Del Perro Pier, burying a body in the desert, hiding from the police, and repeatedly running out of a strip club in his underwear (once while chasing a pair of strippers).
Michael, I've only seen doing depressed, drunken things around his house.
Franklin has a tendency to be exiting a strip club, and generally does little else.
Trevor is by far the most varied when it comes to random shenanigans (as expected). There's a lot more I've seen him do that I can't remember at the moment.