Definition
To go to bed for the purpose of sleeping.
指上床睡覺。
I've been working all day; it's really time to hit the hay.
我已經工作了一整天；現在真的該上床睡覺了。
The kids were exhausted from playing, so they decided to hit the sack early.
孩子們玩得太累了，所以他們決定早點睡覺。
After this movie, I plan to hit the hay immediately.
看完這部電影後，我打算馬上上床睡覺。