(NSFW) What is something that you refuse to try during sex?

We all have certain sexual activities that we don’t care for. Perhaps you’ve tried them and never will again.

For example, I’m not a fan of threesomes. They make me uncomfortable for some reason. I prefer the intimacy of being one-on-one with someone.
I also don’t like to be fingered and you’re definitely not throwing a fist in there.

What are yours? Anything particular at the top of your list?
Do you also have anything you’d like to try, but have yet to?

They can be sexual activities, fetishes, etc.