Green’s Dictionary of Slang

1. a day-dreamer.

1938

J. Curtis They Drive by Night 141: ‘I’m a murderer,’ he said slowly. ‘Go on! So’m I! Shake!’ She held out a hand. ‘Come on, unconscious, get out of it!’.

2. (US campus) a fool.

1932

J.L. Kuethe ‘Johns Hopkins Jargon’ in AS VII:5 337: unconscious — n. — a stupid person.