A Harry Potter is a sexual term which references a man pulling out of the mouth of a woman during oral sex, to ejaculate a zigzag (lightening bolt) pattern upon her forehead.
Hey man! Dude, it was crazy last night. Sheila was sucking me off and I totally gave her a Harry Potter. I hit a little high though and got some in her hair - she was pissed
by Muggle Mouth October 05, 2011