I like this idea. After reading I started getting horny with ideas. I'll go specific with individual posts.
First:
Carnival style game
So have we all seen the game where you roll a ball up a ramp that goes into a hole and when it goes in your horse on the wall moves forward? Keep rolling until a winner.
Doms take their subs, strip them and enter them for the day on this "ride." The sub becomes a "horse" and is put on a contraption like the South Park vehicle from Season 5, Episode 11 "Not in my ass or mouth." The "horse" gets it in the ass and mouth each time a ball goes in the hole and moves forward. Subs stay all day. Winning horses see more hole action.
Doms play the ball game for prizes.
Subs:
https://images.app.goo.gl/QX6wxW7djU34fDL57
Game:
https://images.app.goo.gl/gGSNt2dmVMmcf2Na7
https://images.app.goo.gl/CJ5ic5PGxnnUSGRE7