All that "Hunger Games" and "X-Men" stuntwork has clearly left Jennifer Lawrence in killer physical condition, because her visit to "The Tonight Show" last night (Nov. 18) was basically a non-stop cardio dance workout.

Jennifer and Jimmy Fallon showed off their most magnificent dance moves in the roles of Dez and Dash, the eccentrically-dressed hosts of a late-night infomercial for a series of instructional dance videos called "Come Dance With Us!"

The dances themselves are so entertaining (Bury the Nut = personal fave) that it might take you awhile to notice the actual punchline, or to understand why Jennifer and Jimmy look increasingly disheveled every time the "informercial" cuts and they reappear in their seats in the studio... but once you do, you'll be impressed.