Fans were delighted that f(x) got to perform their full song, "Gangsta Boy" for their comeback stage on M! Countdown on April 29th, and it has generated much interest ever since. Following the performance, a dance rehearsal video of f(x) rehearsing the dance in their SM Entertainment dance studio has been released on the internet, and it was also revealed that it had been cheoreographed by one of SM's favourite dance cheoreographers, Rino Nakasone. Check it out below! Thanks to everyone who sent this tip in.