When you do not want anyone to know you farted.
"Hey Joe did you just fart?"
"No man, my ass has a cold and just butt coughed"!
When you're standing over a putt and are unable to hold a fart in. Much like an uncontrollable cough.
As Joe Witterall stood over the 3-footer to win the Penn-York league golf championship, he was unable to hold in his butt cough, causing him to lip out the putt.