cough cough is used to subtly imply that you know something that someone else doesn't. The person who it is "used on" will then begin to suspect something is suspicious with the phrase "cough cough" and will begin to wonder what it means. Mostly, "cough cough" is pronounced as a word, instead of being actually "coughed out".

Those special times when you can't say something, so you just, ya know, sort of cough...

when your not in agreement with something but the other person things you’re in agreement

The act of semi-discretely littering in a way that looks as though accidentally dropping the trash while suddenly and deeply coughing.

1. any act involving sexual activity with another of your species

When you want to attack someone in the middle of the night at a sleepover. Ex. With Silly sting, shaving cream, etc.

*cough**cough**sneeze* ye
when someones trim is so cold that you gain head top freezing.

commonly used when speaking about heir.
it,s a hazard