They will make an version of Eyelander which says "Hats, hats hats hats.." and not Heads.
Effect: On each kill with melee weapon you steal enemy's hat.
All of this hat nonsense has been a run-up to a new class: The Hat Merchant. He carries a cash register that drops a random hat every 100th time he is killed, but only if he spams the chat channel with buy/sell/trade messages for at least an hour beforehand.