When you are occupying a stall, give a little cough to indicate to others that you are there and should be given the courtesy due all crappers. Practice your cough to ensure that it is loud enough and projects past the stall door. Also work on timing. Also give a cough when you enter a public facility. Highly skilled crappers will give you a cough in return to indicate that they are there and know the rules of crapping too. Loud humming or the shuffling of reading materials can be a substitute but is not recommended as it is not very good etiquette. Toe tapping is also quite effective.
Reading Materials
This is a brilliant time to brush up on your trade publications or gossip mags. While newspapers are acceptable, they can be unweildy especially in a tight stall. Pornography is never the choice of serious crappers. Erections do not lend themselves to the easing of the sphinctor muscles and the free flow of fecal matter.
I'm thinking of sending this as an inter office memo. We have some seriously poor toilet etiquette here. I understand it's tough sometimes to squeeze one out but is grunting and moaning while another occpant is in the room totally necessary? We also have an OSHA issue here, every day someone covers the entire stall floor with powder. I'm not a big fan of cranky ass and I know it can be uncomfortable, but learn to powder your ass without turning the men's room floor into a slip-n-slide.