3. alcohol intoxicated, drunk (probably from the fact that you lose consciousness when you drink to much)Don't bother, he's out cold.
Source: Urban Dictionary.
and out like a light
1. Fig. unconscious. I fell and hit my head. I was out cold for about a minute. Tom fainted! He's out like a light!
2. Fig. intoxicated. Four beers and he was out cold. He sat in his chair at the table, out cold.
3. Fig. sound asleep. After a few minutes of tossing and turning, she was out like a light.
See also: cold, out
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.