The muscle-up is a rare beast – an upper-body exercise that requires both pulling and pushing power and phenomenal core strength to boot.
Those unfamiliar with the move say it's just a pull-up combined with a dip, but a muscle-up is much more than that. It's an unparalleled assault to the upper body, and you have to be strong just to do one.
Hating on CrossFit is trendier than those hipster Ray-Bans your aunt bought you. There are some aspects of CrossFit that deserve your attention, however.