Oh yeah, the place I used to board several years ago had an entire herd of 'em. They'd take over the best arena a couple times a week, all out riding bareback in their halters, flinging their carrot sticks around. It got to the point where everyone else on the property knew better than to ride at the same time, even in the arena on the other side of the barn. Inevitably someone would come off, then there'd be a loose horse in an arena with a half dozen other mostly-wild horses ridden by basically inexperienced riders and all chaos would ensue.

Though, if I remember right, the majority did wear helmets. So there was at least that.

Adventures in the land of the OTTB