Humiliation, being denied sex and having masturbation as my only release, basically being a sub to my wife, while she has a boyfriend turn me on, both in reality and as a fantasy. There’s rarely a specific context that’s important but playing out these roles in a place where people can watch, like a sex club, is a huge rush.
The one thing that is always a part of my fantasies is being told by my wife to clean up the other guy’s cum off her breasts or stomach. I probably enjoy it even more than eating a creampie because licking cum off her body makes the act of cum eating so clear and intentional.