Chris Brown & Drake's ESPYs Bit -- Breezy's Gonna Get Up In Drizzy's Grill

Chris Brown is assaulting Drake again ... this time right in the mouth -- but truth be told it's part of a comedy skit at Wednesday's ESPY awards.

Here's what we know from the rehearsals ... the skit begins in a law office, then a locker room and finally in a dentist's office with Clippers star Blake Griffin standing over Drake like Steve Martin in "Little Shop of Horrors."

We're told ... Blake looks like he's about to go in deep, when a frightened Drake blurts out, "Are you really going to do this?" Then -- suddenly -- Chris walks in and answers, "No, I am!"

Pretty interesting ... Rihanna has become a punchline.