It is gas that one has either swallowed whilst eating, or (principally) produced by the breakdown of the food one has eaten, producing, mainly, methane. It goes through the gut and intestines and has one way out only. The pressure builds, which one feels, so one does a little strain and the sphincter opens, and one farts. Decomposing food odours are mixed in with the gas. It is an rapid expulsion of gas from one's bottom, often hilariously.
- Alex Nicholls
- Alex Nicholls