Sarah Larson, the go go dancer ex-girlfriend of George Clooney, reportedly partied it up at the Sundance Film Festival over the weekend.

The Las Vegas cocktail waitress was seen “provocatively grinding half a dozen men on the dance floor — all at once” at the Hard Rock Hotel & Casino after-party for the film “The Vicious Kind.”  And no, Larson wasn’t invited.  She and her entourage sneaked in through the back door.

The dirty dancing troupe included Larson’s former flame, Las Vegas-based editor for 944 magazine, Ryan Doherty. “Sarah was grinding on Ryan all night, her legs wrapped around his waist, massaging the small of his back,” said a source.

At the end of the night Larson narrowed it down to one man who wasn’t part of her dance floor escapades. According to sources, she was seen sneaking out the door with Ashlee Simpson’s ex Ryan Cabrera.

Way to keep it classy, Sarah.

Sarah Larson photo: WENN/Fayes Vision

Ryan Cabrera photo: WENN

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Filed under: Celebrities, Hollywood Hookups