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 see Benoit at Crossfit yesterday. He was REALLY CROC'ing out!
.. Hey, you ready for the meeting? Hell yes, let's Croc Out!
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)