During the sexual act of 69ing, while the girl is on top being pleasured by the male she then poops on the males face/mouth. It can either be planned or not.
This word can also be used as a filler when you have nothing else to say. It is definitely a party pleaser.
"Hey Jack how was your date last night?"
"Hey man, It was going great until she Poopty Nined me."
" Uhhhh Gross man!"
"Babe get in here! I want a Poopty Nine the crap out of you! Literally!"
