it's a dance. the harlem shake started by a homeless crack head dude that would dance in between periods of those and1 games at rucker park. it caught on (15 years later), because trap music. to enjoy trap music you have to be on drugs, hence, why some folks harlem shake to it. kids and some grown folks think crackheads are funny, so, they mimic them and post it on youtube.
is he doing the harlem shake or did he get shot?