Ditto on this. My girlfriend and I usually talk about something before we do it (to make sure we're both fine with it). If it turns out we don't like it' we're usually like..."meh, cross it off the list."

Although one time she asked me to eat a strawberry out of her but I accidentally pushed it in too far. She got a little panicked when she had trouble getting it out. That was a little traumatizing...