"Farting: Awkward! But then, when is it not? Farting during sex isn't a problem everyone faces, but it's not exactly uncommon either. Think about it-you're uninhibited, you're vulnerable, you're moving your body in new and exciting ways. If you're having anal sex, you're actually pushing air up into your nether regions, and it's probably not going to stay put.
Even though it's natural, even though everyone does it, passing gas will never cease to be a blush-worthy occurrence. On the plus side, it will also never stop being funny. Rather than worrying, do your best to laugh it off. You also might want to crack a window while you're at it. You know, just in case.