Every manager writes a punishment on a slip and drops it in a bag; the loser draws one at random and must do whatever they pull. The randomness is the cruelty, your fate might be authored by the league's one sicko. Slips are vetted by the commissioner for legality and little else.
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.
Seen in the wild: gridironexperts.com · 4for4.com · fantasyfootballunlimited.com