“How do I convince her
to give up the butt?”

How do I convince my girlfriend to give up the butt?
-John

Honestly, why do I answer these anymore?

John, I'm assuming you asked your girlfriend for anal sex. And I'm also assuming that she said no. Actually, the scene I'm picturing in my head involves her slapping you silly while squealing "Ew! Gross!"

Sorry to break it to you, John, but that kind of reaction means no anal for you. If your lady doesn't want it, then you should respect her boundaries.

But if you really can't live without anal sex, maybe you should get yourself a more open-minded girlfriend, John. Or maybe you should beg and wheedle and guilt-trip her until she breaks down and consents. Or until she dumps you for being such a whiny, anal-sex obsessed loser.

Honestly, I can't blame her for being squeamish. For most women, that area is off-limits. Which, of course, means that men will do anything to get down there. It's new! It's different! And men love putting their dipsticks into the vast unknown!

Simply put, the anus is not an erogenous zone on women. Men have prostates that make anal sex pleasurable, but women have nada, zilch in the area (anything good, that is). If your girlfriend agrees to have anal sex with you, it would be pretty much for your pleasure only - which means that maybe you should consider doing something nice for her in exchange.
Before I get any nasty emails: yes, there are women out there who enjoy anal sex. Probably enough women to populate a small island. A very adventurous, open-minded island.

But I digress. John, if you're really interested in having anal sex with your girlfriend, sit her down in a non-sexual situation and explain, in detail, why it's so important to you. Not the lame reasons why ("I saw it in a porn and it looked awesome!") but good reasons ("It'll add variety to our sex life"). If she still says no, then you're going to have to be satisfied with boring old vaginal sex.

But if she says yes, you'd better stock up on lube. And be prepared to deal with the unpleasantries. Your girlfriend may be sexy, but she certainly isn't storing fluffy bunnies and rainbows up there.