The loser of the league's 'Mayo Bowl' matchup works through a league-set amount of plain mayonnaise by the spoonful on camera. Quantities vary by league cruelty, but even a cereal bowl of mayo is a life-changing amount of mayo. Keep portions gross-but-reasonable; nobody needs a hospital trip over condiments.
Heavy sentence
Severity 4 punishments are the ones people talk about for years, which is exactly why they need full league buy-in before week one. Put it in the constitution, set the deadline, and agree on proof requirements up front.