When I got a little bored in GTA4, I borrowed one of those Annihilator helicopters and played "blender" with the traffic in Star Junction, and when that got old I went and kamikazed into the tour helicopters until they fell down. I got one to crash into the pond in Middle Park. Also, I was always stacking up a whole lot of cars and blowing them up, but just about everyone does that.
In the first Age of Empires, the first time I went into the scenario editor I placed down about 50 of every unit for every team, and then test played. That was fun.