Before the season, every manager files their own personalized punishment, tailored to their specific fears and running gags, and signs it. Whoever finishes last executes their own pre-agreed sentence. Self-authored consequences eliminate the post-season refusal problem, which is why commissioners love this system.
Budget note: this one costs nothing but dignity, which makes it a strong pick for leagues that would rather spend the pot on the champion than on the loser's downfall.