Jennifer Lopez surprised fans by joining Tom Cruise on stage for a dancing duet at Sunday's MTV Movie Awards.

As Ludacris blared, Cruise, who was dressed as his Tropic Thunder character Les Grossman, entered the stage solo and began dancing, even grabbing his crotch at one point.

Then Lopez's tune "Get Right" started playing, and she emerged.

The two showed off risque moves: Lopez smacked Cruise's booty, and he tried to reciprocate, but she rebuffed his advances.

The audience loved the routine; wife Katie Holmes was smiling and clapping.