Question: Why do farts stink?

Hayley Moulding answered on 18 Mar 2016:

So the smell of those farts comes from little things called ‘fatty acids.’ These little acidic molecules add to the smell but so do other molecules that contain sulphur and nitrogen. The bacteria (again, those pesky bacteria!) cause the fatty acids to be made and the activity leads to smelly smelly farts. Also breaking down protein can lead to more smell and sulphur being produce! Ewww! We can’t help it though. Sometimes foods high in protein or fat make a more horrible smell!