Move over, Chiefs ... one Kelce brother is all briefs now!!
Travis Kelce's older bro, Jason, made a helluva entrance at a charity event in Sea Isle City on Wednesday ... stripping down to a pair of tiny, U.S.A-themed undies to get the party started.
He, at first, had shorts on when he entered his annual Team 62 at the Ocean Drive celebrity bartending shindig -- but in order to rile up the crowd, he tore 'em off to reveal far more of him than the public's used to seeing.