Is There a Word Conked out?

1 of a machine : to stop working properly My car's engine conked out this morning. 2 : to fall asleep I conked out on the sofa last night.

Where does the phrase conked out come from?

Originally, conk meant "punch in the nose," from 19th century slang for "nose," conk. Later, the word became World War I military slang, for the sound a stalling plane engine makes when it "conks out."

What is the meaning of zonked out?

verb. (intr, adverb) slang to fall asleep, esp from physical exhaustion or the effects of alcohol or drugs.