Red Ring of Period. The red ring of blood left at the base of the penis after a man has sex with a woman who is on her period.
Dude 1: "How'd your date with Amber go?"

Dude 2: "Man, I plugged my joystick into her sexbox and got the RROP."

Dude 1: "Oh shit. Hope you were wearing a condom."
by TippyGoesLive! June 19, 2010
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