Why do men like to have sex with a woman's ass?

The answer to basically any question of the form “why do $people like $sex_thing”^1 is “because it’s fun.”

Throughout my life, until just recently, I’ve had girlfriends who enjoy receiving anal sex, and I’ve always been willing to do it, though I’ve never been a huge fan; too much work for something I personally didn’t find particularly interesting.^2

Why?

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I now have a lover who is a passionate and enthusiastic fan of anal sex, and she has an ass that is…um, extraordinarily accommodating and a great deal of fun. So, for the first time in my life, I have a partner I actively enjoy giving anal sex to.^3

1. Yes, I prefer underscore_notation to camelCase. It’s easier to read. Change my mind.

2. Giving, anyway. I’ve always been a big fan of receiving, which is why almost all my lovers have been quite skilled with a strapon, and I even own a patent on a new type of strapon.

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3. Yes, this does mean I’ll do things during sex I don’t necessarily actively enjoy myself. I think one of the hallmarks of a good lover is willingness to do things that get your partner hot even if they don’t necessarily rev your motor.

Because it’s fun. That’s it. It’s enjoyable and feels good. It’s really not rocket science.