Soulja Boy isn't letting Chris Brown off the hook for the celeb boxing match that never was -- in fact he's smack talking like they're still getting in the ring.
Soulja dragged Chris, verbally, during a concert in Minneapolis this weekend ... claiming CB agreed to the fight, signed on to fight, but then backed out ... out of fear.
Chris' explanation was he wasn't comfortable with the people trying to make money off the fight. Soulja's definitely not buying that.
We'll say this, he does look a little more swole. But this is real tough talk from a guy showing off his tightie whities -- and a lot of 'em!