"...he's a leper for a reason."
2. An acquaintance that constantly fails to follow through on a prior arrangement or obligation.
- Derived from the term leprocy. Leprocy is a communicable disease that causes lesions to the skin and disfiguring of organs. This is followed by flaking of the skin. Flaking is used in direct correlation with leper.
"I had talked to Mooney two times yesterday on the phone and he was supposed to meet me here two hours ago! What a leper!" (a similar word is Flake)