I usually don’t recommend holding in a fart, but if you can consciously help it, then don’t let it out in one of these places.
Such as the gateway arch transport, there is no escape and it’s just cruel to unleash your cloud of hatred here.
Most churches have padded chairs, but you might find one that has the old wooden pews. Just blame your pillar of cloud on the spirit moving you, many church goers won’t quench the spirit.
During an MRI
You absolutely can’t move and it might destroy the image they are trying to capture. Plus only you get to smell it, and that’s no fun.
I know it’s cliche, but if you must, wait until you are about to get off. It’s the quickest way to move your stink from the ground floor so that people on the 13th floor can enjoy it.
It’s probably the easiest way to get the doctor to enter the room. Once you unleash it they will enter and probably put you on a pro-biotic regimen. Bonus points for holding it in after a prostate exam.