One eyebrow, shaved clean, no drawing it back on. The face looks subtly, horribly wrong for six weeks, and everyone the loser meets can tell something is off before they can say what. Two eyebrows is the repeat-offender rate.
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.
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.