This occurs in classrooms or other large public settings. Usually one person begins to cough, and other people who needed to cough, but were afraid to do so, join in, causing multiple coughing sounds at the same time.
Person 1: Ugh why does everyone have to cough at once, it's so annoying.
I was coughing a lot last week, and I accidentally farted at one point. My mother was in the room, so I told her I was "coughing out of both ends" to hide the shame.