Stands for Unidentified (or Unknown) Drinking Injury. Any kind of injury that is impossible to explain due to the fact that the injury occurred while drunk or otherwise in a wasted state.
When I woke up the next morning, there was an abundance of U.D.I.'s: scrapes, bruises, open flesh wounds -- I thought to myself, "I don't remember walking through a swamp or viciously attacking a laundry hamper."
by slurogue February 27, 2009