The original Cha Cha Slide is a line-dance song by Chicago DJ Casper, first released in 2000 and long played at parties, weddings and school dances for its simple call-and-response steps. The Uno reverse card, from the classic card game, later became an online shorthand for turning a situation back on someone. Creators combined the two ideas into reversed edits of the track, sharing them on soundboards and short-form video as a quick way to signal a comeback. The joke survives because almost everyone recognises the tune, even played backwards.