Slag for "Cunt Rag", a cloth used to aid in menstruation, a tampon.
Person 1 - So I was fucking this bitch in her ass and when I was about to nut, I pretended to unload in her ass. She freaked out and turned around and I shot it in her face. I call it the "Houdini".
Person 2 - You're such a fucking c-rag.