Michael Sam went straight "Over the Top" in a Dallas bar -- arm wrestling a dude who called him a "p*ssy" ... and TMZ Sports has the video.
Here's the deal ... Sam (the 1st openly gay player to be drafted by an NFL team) was hanging out at Bottled Blonde when he started chatting it up with Miami designer Jared Lang.
Lang playfully challenged Sam to a test of arm strength -- and Sam obliged. They clasped hands, Lang teased Sam by jokingly calling him a "p*ssy" .