Ah, the dreaded sleeping farts. Those are some of the worst, because when you're sleeping uner the covers and just keep farting, guess what's going to happen when you lift the sheets? I always try to avoid getting a warm blast of my own farts in my face by lifting the covers, sticking my butt out, and farting. But this takes a lot of energy and sometimes it's just so nice and cozy in your bed-- you just don't wannt lift your butt out into the cold.
Another thing about sleeping farts I dislike is that sometime you don't even know you fart. For instance, when I am crouching over a desk sleeping in class, I am always on the alert for gas problems. When I am bending my body like that, gas buildup is always a problem. And if I am unconscious and have no clue that I am farting, it just adds to further embarassment.