Slapping wrist action (usually with some minor hip thrusts) used while dancing, the "spank" is typically in the air, though in some instances contact with a partner is made. Used to simulate coitus, especially "doggy-style."
Girl 1: Did you see that?
Girl 2: What?
Girl 1: When Bev wasn't looking Bob got behind her and gave her a dance spank.
Girl 2: You know she loved it!
Girl 1: Yaaa!