The Dance Craze is everywhere and now it invade the Anime World. Gangnam Style is popularized by a K-Pop rapper psy, I'm not a K-Pop Fan so I don't care whatever it is.
if you're intersted you can check in their wiki:
"Gangnam Style" is a 2012 K-pop single by the South Korean rapper Psy. It has been featured in broadcasting networks such as CNN and Bloomberg, mentioned by numerous celebrities, and has also led to various user-generated parodies and reaction videos from all over the world...
Adventure Time in Gangnam Style Dance
OnePiece, Luffy, Zoro and Senji in Gangnam Style Dance