It maybe related to you BEANS consumption

may i recommend to you the Cough of Obfuscation^TM^. Strategically timed coughs can cover all manner of untimely and inconvenient noises produced by the body. It's also useful it public toilet stalls.

Holding your farts is one of those things that goes from impossible to trivially easy with practice.

Like walking, speaking, playing a Bach fugue on the piano, doing a backflip, or memorizing your ten digit phone number, it’s one of those things that doesn’t even seem possible when you first try.

So yeah. The social norm in public school and in basically the rest of the civilized world is to hold your farts until you can release them in a bathroom, or outside. If you release them outside don’t do it immediately before coming in because it takes time for the smell to dissipate.

People are farting. They just know how to do it without making noise most of the time.