Mistress_Elizabeth said:
I know that most people are just fantasizing and are not serious, but just in case someone isn't: don't try to "surprise" the other person with a "mistake." You'll hurt the other person by trying to do that without any preparation, and no, it doesn't matter if that person is "submissive".
Since it sounds like you're trying to take a jab at me; I never said there wouldn't be any preparation. Also some women actually enjoy painal believe it or not.
It obviously shouldn't be done in an unsafe way or anything but with someone that is submissive, a bit masochistic, and had some good anal foreplay then it's usually not a problem.