It's when you are really going for it - whether it be at work (doing a big deal, showing your expertise or kicking somebody's ass who made you mad) or showing off at Sports or with the opposite Sex.
You're showing the world that you are the man (or wo-man)...
... oh man, did you seeBenoit at Crossfit yesterday. He was REALLY CROC'ing out!
.. Hey, you ready for the meeting? Hell yes, let's Croc Out!
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi