I have two principles that establish all my limits.
Number One—I will not do anything that is not consensual—not knowingly, that is. I might start to do something I think is pretty tame only to find out it really freaks-out to my partner. Of course I would immediately stop, apologize and explain I didn’t know they didn’t like that. But I would still have inadvertently violated my rule. It’s just that when petting gets heavy and starts to go beyond petting, stopping to have a scholarly discussion about each new step takes the wind out of those romantic sails in a heartbeat, so shit happens.
Number Two—There are some things I wouldnt do even if a partner wanted me to. Those are things that cause permanent harm, or carry a serious risk of doing so. Some people get off on being choked a little just as they approach orgasm, then having the hold released and experiencing the rush of blood to the brain just as they peak. I’m sure it feels great when it works, but I don’t want to explain how it accidentally didn’t work at a coroner’s inquest. Anything that causes or might cause death, disease, permanent disfigurement or disability is off the table for me.
That would make having a wild orgy off linits, because it would be nearly impossible to rule out the risk of STDs like AIDS. So even if my partner wanted an orgy, I’d have to think long and hard about how to arrange it without violating Rule 2.
I figure for partners that want such edgy, dangerous play, there are plenty of ghouls and vampires and folks with a secret death wish out there. Someone wanting such treatment can seek them out, but I’m definitely net their type of guy.
Outside that, every paraphilia you’ve ever heard of and the rest of them you haven’t heard of but that are out there somewhere are fair game if my SO wants to give them a try and they clear Rule 1 and 2. ANYTHING. I do not have a working eeewwwww organ.