What about using the mouth as a substitute vagina, Linda? What about using a latex vagina as a substitute for a real one?
Here's a clue for you: if you don't like a particular sexual activity (or any other activity, for that matter), DON'T DO IT!! If someone is forcing you to have anal sex, have them arrested.
Here's another clue: the sexual activities of other people are none of you damn business. Stop thinking about it and do something productive instead.