demimooresidebyside460.jpgdemimooresidepic.jpgGetty Images For Chanel

Demi Moore surfaced at Chanel's Art Basel Barbecue for in Miami, and Ashton Kutcher's ex was ready to party!

The 50-year-old actress, wearing a grey romper and peep toe heels, showed off her very sculpted legs. However, many at the party say Moore was acting very bizarre ... and even "grinding with fellow party-goer Lenny Kravitz."

Demi's young beau American art dealer Vito Schnabel attended the party with her. Sounds like Demi is quite the dancer. Whip it good!