sack out

Outgrowth of the earlier idiom, to hit the sack, with possible influences from other senses of to sack (“tackle, pillage”, verb), and to sock (“hit, slam”, verb), providing an implication that sleep has been thrust upon a person.

sack out (third-person singular simple present sacks out, present participle sacking out, simple past and past participle sacked out)

1. (slang) To fall asleep, usually from implied exhaustion.

   The kids sacked out in the back seat before we made it home.

• drop off
• doze off
• See Thesaurus:fall asleep

• sack