Let's take an example from my own personal experience. You're standing in line at the post office to pick up a package, what is in the box? That doesn't matter. It definitely isn't jars of illegal pickled tiger testicles from India that is for certain. So there's a long line at the post office and it's moving slow as usual. You've been standing in line for close to an hour and are almost at the front when the urge to poop hits you like a grand piano dropped off an office building. You look around for a bathroom, but it's a post office. You look around at everyone else in line frantically trying to figure out what you should do. The people behind you smile because they know if you leave they're going to move up a spot, but you can't give up! You're so close! If you left, the entire day would be wasted and you'd have to go through it all again on Monday spending all that time without your jar of tiger balls. And before you can even take a single full step out of the line you let loose a fart that has with it a gigantic load of feces. It's official. You've shit yourself.
The question is what to do next. Now any pantshitting rookie would just jet right out of there and expose their crappy wet ass to everyone in the post office as they laughed. That's the first thing you DON'T want to do, especially if you're wearing white pants. First you want to point at the oldest woman around you and say "EXCUSE ME, MADAM!" People will usually assume an old lady shat herself over a healthy white pantsed man. Then keep pointing, don't let your hand drop. This puts all the focus on your pointing. People's thoughts will be more locked on "How long is this guy going to point at this old lady?" versus "Wow, that really smells a lot like shit." Hold the pointing until you're at the front of the line and complete your business. Then once you have your package walk out of the post office backwards with your ass facing away from everyone, keep pointing if you can. I guarantee once you leave the room people will be so confused they won't even remember you shit your pants at all. They'll think it's part of a hidden camera show or something. THAT is how you shit your pants in public.