The loser registers for, pays for, and sits a full real SAT in a room of stressed high schoolers, and the score gets posted to the group chat, and in some leagues engraved on the loser trophy. One of the first punishments to go viral and still the gold standard for psychological damage per dollar. Studying is optional but the mockery for a bad score is not.
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.