An affliction that often occurs to people who chronically don't think carefully enough about what they are saying in a conversation. Saying something thoughtless that might hurt another's feelings is something we all do occasionally, but if it happens more than once or twice per month, you might have foot-in-mouth disease.
When Bill dissed his sister's new boyfriend to his buddy Richard, he didn't bother to look around and make sure she was out of earshot. Richard said, "Damn, Bill, she's in the kitchen only a few feet away! D'ya got foot-in-mouth disease or somethin'? "
Exactly what the term implies. It refers to someone who seem to always say the most inappropriate thing at the most inappropriate time.
Commonly also referred to as CFMD. There is no known medical cure for this ailment. It tends to be hereditary and is usually passed down from the father's side of the family. Typically the gene is passed from father to son but it has been known to appear in females. Sufferers of this malady also tend to lack class and moral terpitude especially when surrounded by groups of people. They also tend to tell really inappropriate jokes that includes racist and or sexist comments and wonder why they are still single.
CFMD's Wingman: You can't just say that to a stranger especially some hot chick you have no chance with. You must have Chronic Foot in the Mouth Disease like your daddy.