Unfortunately, they do. The fart produces a large lump of noxious gas that remains trapped in the recesses of your pants. This gas can't escape through your pant legs, nor through the waistband; it is permanently trapped. This can be a deadly situation, as taking your pants off would release the noxious fumes so potent, it could choke a monkey. However, the more you fart, the more concentrated this gas becomes, and the more deadly it can become.

I suggest the possibility of never farting again. You can do this by not wearing any pants. This would allow the noxious fumes to safely enter the Earth's already dying atmosphere and dissolve into the air. You might notice a faint putrid odor, but it won't last long. No known side effects are to occur when this happens, but you can't be too careful.