In this 1941 video, Russian soldiers are seen engaged in a precursor of the modern dance-off; to drive home the point, some wag has set the proceedings to Run DMC's "It's Like That," which is curiously fitting.
Cossack (or Hopak) dancing originated in southern Russian and Ukranian military communities. The general plan was to have a battle, win, then return and have a big dance off with all your comrades. The party was male-only, of course, and often involved pantomime style re-enactments of battlefield moments, with sabres et al.
(Thanks, Dunchead, via Submitterator!)