hit the sack

Từ điển WordNet v3.1 - WordNet Dictionary

verb

prepare for sleep
- I usually turn in at midnight
- He goes to bed at the crack of dawn
• Syn:
go to bed, turn in, bed, crawl in, kip down,
hit the hay, sack out, go to sleep, retire
• Ant:
turn out (for: turn in), get up (for: go to bed)
• Hyponyms:
bed down, bunk down
• Verb Frames:
- Somebody ----s