Innny or outie?

Sooo a couple years ago before I got in a relationship one of my very good guy friends told me he liked me, we started talking and after a year of talking we started doing stuff, well before we did anything to dirty he asked me is your pussy an inny or an outtie? Honestly I had no clue what he was talking about so I never answered and ended that friendship 😂😂 any clue? What he meant? Lol