The phrase was made popular by the revolutionary, socialist band, Rage Against the Machine in the songs "Take the Power Back" and "Freedom". It was used in the context of inciting rebellion against the current capitalist economic system, although this meaning is not exclusive to the phrase.
Coach: C'mon guys. I know it's the bottom of the ninth and we're down two runs. But you all need to get focused. You all need to get the led out. I don't want to see any pussying out. You run like a bat out of hell from base to base. C'mon! Bring that shit in!