T-Boz -- I'll Fight Rihanna, And Kick Her Ass!

T-Boz fired off another salvo in her naked war with Rihanna ... this time upping the stakes by essentially challenging her to a fight.

RiRi and T-Boz squared off earlier this month after T-Boz trashed RiRi for regularly showing way too much skin. Rihanna fired back with a twitter pic of a topless TLC -- i.e., Rihanna called her a hypocrite.

So it was T-Boz' move when we got her outside Bootsy Bellows Thursday night ... and she threw gas on the flames.

So we gotta ask ...