When you swallow food, water or saliva, you also swallow small amounts of air, which collects in the digestive system. Gases can also build up when you digest food. The body needs to get rid of the build-up by farting (flatulence) or burping (belching).
Thanks for asking
How come when you burp you say pardon
And when you fart you laugh ?
It’s usually a build up of gas that makes me fart
Nothing in particular sets it off
I went to school with a kid who could fart on cue
That was funny listening to him farting all the way through certain lessons