Trey Songz -- I'm Totally (Maybe) Banging Colin Kaepernick's Ex

The fitness model who reportedly hooked up with Colin Kaepernick is now rumored to be messin' around with Trey Songz ... and Trey isn't exactly denying it.

The woman in the mix is Brittany Renner -- the self-proclaimed leader of the "Fit Thick Army" -- which has become a social media battle cry for ultra-fit women who embrace their curves.

So, when we saw Trey out in Hollywood this week -- we had to ask how he felt about Ms. Fit Thick ... and he responded with high praise.

He also had a chance to put the rumors to rest ... but didn't.

Which begs the question -- they bangin' or what?