It is when you are masturbating, then promptly bend over and shove your own fist up your ass, while continuously masturbating, as this is going on, you are attempting to suck your own penis, making the fist go farther up the ass hole. Remember, it's not the charlie if you're not shoving the fist in, full fist, no "one finger, two finger" bull shit. Just, fuck no.
Friend: NO FUCKING WAY! Are you serious?! I've been trying to pull that shit off for ages!