When you find a girl passed out, typically at a house party, you lay down next to her and put her hand around your penis. Then you put your hand over hers and proceed with a stroking motion. After you finish take her hand and wipe up the jizz. Then close that hand into a fist so she wakes up with a nice sticker surprise. She will wake up and say "Ninja, Please!"

A casual invitation / threat used by an individual that is not afraid of fucking someone up.