To suddenly and uncontrollably fall into deep sleep. Typically in the form of a full night's rest or extended nap. Derivative of the word "narcoleptic," but not actually associated with it.
"Sorry I narced out last night in the middle of the movie; I really wanted to watch it with you."
1. Someone who rats another out, usually regarding illegal activity.
2. A person who sleeps alot. Thus they are jokingly called "narc", short for narcoleptic: a person with the disease of narcolepsy, who as a result does not have proper control over sleeping/wakefulness.