Bathroom Etiquette

Men don't talk in the bathroom. That's just a general rule. Oh sure, if it's only a guy and a co-worker or a buddy, they may chat briefly. But if it's a bathroom with other people there, everyone is quiet. They do their business (so to speak) and then they leave.

So you're standing at a row of urinals doing your thing. Someone walks up to use the urinal next to you. And while you are standing there, they emit the loudest, longest, fart. What if it's someone you know?

Do you say anything, or just keep your mouth shut?

Does what happens in the bathroom, stay in the bathroom?

What would Miss (or Mr.) Manners say?