The premise is simple: a 30-second video set to the tune Harlem Shake by New York-based DJ Baauer. For the first 15 seconds, one person dances while everyone else in the room remains as they are. Then, the beat drops, and everyone kicks off.
Unlike Gangnam Style, the Harlem Shake has no specific choreography. Most dancers interpret their moves, with crotch thrusts, arms flapping and handstands among the favourites. Every video has put a different twist on the dance routine, with many donning esoteric costumes and fancy dress.
The Harlem Shake phenomenon has been around since the 1980s, but this latest meme has catapulted it into mainstream culture. Norwegian soldiers, firefighters and various office staff are uploading their efforts online.