Coughing, clearing your throat, or making some noise while in a public bathroom stall to let people entering the bathroom know not to even try the stall door. Especially used when door lock is missing or doesn't work.
man #1 enters bathroom and heads towards stall
can cough comes from behind stall door man #2 uses different stall
When you've consumed a large amount of greasy food (typically KFC or other fast food) and the accumulated grease and mucus in your throat forces you to cough.
This is the fake cough that non-smokers give to someone smoking, even in an outdoor setting. It is generally characterized by one dry cough and accompanied by a dirty look.
Fred: Hey, I think Mike is getting sick. I was outside smoking, and he walked past me coughing.