rack out

Related to rack out: racks up

rack out

To sleep or go to bed. "Rack" is a slang term for a bed, as well as for sleep itself. I just need to rack out for a few hours, and I'll feel as good as new! We should rack out soon, we have an early start tomorrow.
See also: out, rack
Farlex Dictionary of Idioms.

rack out

Sl. to go to bed and to sleep. I'm really tired. I've got to go rack out for a while. I racked out until nearly noon.
See also: out, rack
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

rack out

Go to sleep, as in I racked out about midnight. This slangy expression, as well as the related rack time, for sleeping or snooze time, use rack to refer to being laid out on a framework, here a bed.
See also: out, rack
The American Heritage® Dictionary of Idioms by Christine Ammer.

rack (out)

in. to go to sleep or to bed. (see also rack.) What time do you rack out?
See also: out, rack
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • bed down
  • bed down (some place)
  • bedding
  • go to bed
  • put (someone or something) to bed
  • put something to bed
  • put to bed
  • die in (one's) bed
  • die in your bed
  • bed down some place