play bow
n.— «Social play has its own vocabulary. Dogs have a particular body posture called the “play bow”—forelegs extended, rump in the air—that they use as both invitation and punctuation. A dog will perform a play bow at the beginning of a bout, and he will crouch back into it if he accidentally nips too hard and wants to assure the other dog: “Don’t worry! Still playing!”» —“Taking Play Seriously” by Robin Marantz Henig New York Times Feb. 17, 2008. (source: Double-Tongued Dictionary)