A phrase within the pro-wrestling community to basically say "Screw off" or "Fuck you" without having to say anything.
The person you're generally talking to is angry at you, almost to the point of beating you up. While they're at their high point, you walk away making them feel like an idiot.
This is based off wrestler Samoa Joe, who in wrestling matches usually walks away when an opponent tries a high risk maneuverer.
"What are you gonna do if he yells at you?"
"Listen to me, you better start showing some.."
-Person pulls a Joe It-