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The act of humping a girl with your knee, ever so slightly, when making out so that it gives her pleasure. Mostly used by couples who want to stay virgins.. for some reason or another.
Bryant: "Why do you have a hole in the crotch of your jeans?"
Jamison:"Oh because Robbie was baby reverse rhino humping me last night. We both have purity rings, so its gonna have to due."
by JamieandRobie May 16, 2011