They may be bad, but they're perfectly good at it!

At Sunday's Billboard Music Awards, Rihanna teamed up with Britney Spears onstage for a live rendition of their sexy "S&M" remix duet.

And Rihanna, 22, and Spears, 29, didn't disappoint fans performing the bondage-themed pop smash. Both clad in latex bodysuits (Rihanna in white, Spears in black) the duo writhed on the floor, pole danced, brandished whips and chains . . . and engaged in the sexiest pillow fight ever!

Watch the kinky duet now.