It's so subjective! Things I talk about with my Domme friends that would make my vanilla friends run away screaming, that I don't even think are pg-13 anymore.
There's a really funny sketch from the show 30 Rock, where this character and her partner who are notoriously EXTREMELY kinky start to run out of kinky things to do with each other so they invent a fetish called "normaling" where they treat each other like a regular married vanilla couple to get their rocks off.