RIHANNA TWERKIN' OFF To Drake Song

Source - TMZ

The following video of a twerkin' Rihanna will probably upset Chris Brown for two reasons: 

1) It's sexy ... and she's reportedly cut him off from tappin' that ass. 
2) She's twerkin to a Drake song ... Chris Brown's mortal enemy. 

The footage was posted by one of Ri's friends -- showing the pop star gettin' down to A$AP Rocky's song "F**kin' Problems" -- which features Drake. 

Rihanna twerking

•  Chris diss
•  Harmless fun

During the clip that was posted, Rihanna shakes her ass during Drake's verse.

It seems to be a thinly veiled dig at Chris -- considering he and Drake hate each other so much, they brawled at W.i.P. nightclub in NYC last year.