Talk about adding insult to injury -- 49ers quarterback Brock Purdy was forced to rep his college rival after Iowa State lost to George Kittle's Iowa last weekend ... showing up to his media availability decked out in a Hawkeyes mascot head!!
The pair of Niners teammates placed a friendly wager when their alma maters faced off Saturday against each other ... and, unfortunately for Purdy, the Cyclones lost, 20-13.
Purdy -- who went to Iowa State for four seasons -- held up his end of the deal at Thursday's press conference ... rocking a big Herky the Hawk head as he took the stage.
The whole room thought it was amusing ... and Kittle thanked Hawkeyes staffers for getting the mascot head to SF.
"Go hawks @HawkeyeFootball @brockpurdy13," the tight end said on X. "Shoutout @TylerBarnesIOWA for getting this herky out to cali!"
Kittle also joined in on the fun ... throwing on his former mascot's head as well.
Purdy isn't the only NFL QB taking Ls by placing bets on his former college team -- Aaron Rodgers had to wear Auburn gear after Cal lost to teammate C.J. Uzomah's Tigers.
Bet at your own risk!!