What you sandwich declarations of disbelief (in a another person's statement) between on the internet when you don't realize that *cough* is not even a close approximation of actually coughing. See, when the words are spoken, you may actually be able to mask the words by feigning a cough or sneeze. Typing the word "cough" only makes you look about as stupid as the people who think they need to type sarcasm in parentheses at the end of every witty, sarcastic thing they say.
Some Guy: I got a 5000 on my SATs.
Another Guy: *cough* Bullshit! *cough*
Some Guy: I was obviously joking, asshole. And this is the internet. typing stars around the word "cough" really doesn't begin to accurately simulate coughing.
Used on forums, chat, etc. to represent awkwardness, or break silence. Rarely used to actually represent coughing, unless someone is explaining how they have the flu or something.
1. Denny: So...
2. Greg: I don't feel so good :( *cough*
1. Used mostly on a chat, or a forum, as a response to something awkward.
2. Used to tell others you have a cough or something.
*Any clash between real names in the example is entirely coincidental*
Jamie: Hey whats 1 + 1?
Jack: *cough* Dumbass *cough*
Jamie: Hey, hows it going?
Jack: I *cough* have a cough.