This is a good one, but I think it's not all shame. Concealing farts in public is a game of skill. You must consider how to position your body so that no sound is made. How quiet is the area you're in? Are there others around who could conceal the true farter? Are you able to discreetly move to another location so that by the time the smell arrives you're no longer a suspect?

You also take into account your last eaten foods and recent farts and how they may result in large smell or sometimes no smell. It's a big game of strategy and execution to be a covert farter.