Green’s Dictionary of Slang

rack v.2

[rack n.2 (3)]

1. (orig. US black) to go to sleep.

[US](con. 1940s–60s) Décharné Straight from the Fridge Dad 151: Rack ’em back Pull up the covers and go to sleep.
[US]Prison Slang Mommyblogger 23 Sept. [Internet] Its time to rack in and red tag until she can learn how to be on the one.

2. (US, also rack in) to sleep; thus racked out adj., asleep.

[US]Baker et al. CUSS 180: Rack [...] Rack it [...] Rack out [...] Rack, get [...] Rack, go Go to bed (not sexual).
[US]D. Jenkins Semi-Tough 90: Everybody else is still racked in and I guess I’m up early.
[US]G. Underwood ‘Razorback Sl.’ in AS L:1/2 54: rack ‘bed, go to sleep’.
[US]J. Doyle College Sl. Dict. [Internet] rack [U. of Oklahoma] to sleep.
[Aus]B. Moore Lex. of Cadet Lang. 291: rack [...] to sleep. As a verb the term is usally (to) rack out (occasionally also (to) rack over).

3. (also rack with) to seduce a woman, to make love.

[US]L. Durst Jives of Dr. Hepcat (1989) 8: Oh yes! In every park there will be sacks where you rackem back.
[US]R. Price Ladies’ Man (1985) 131: I know what I’m doing when I rack, but that night [...] I felt like a high school senior. I came right away.
[US](con. 1985–90) P. Bourjois In Search of Respect 294: ‘She ended up being Ray’s woman.’ [...] ‘They used to rack in them days.’.

In compounds

rack date (n.)

a seducible female.

[US]Eble Campus Sl. Apr. 3: rack date – a female who can be easily persuaded into bed.

In phrases

rack out (v.)

(US) to fall asleep, to go to bed.

[US]Dundes & Schonhorn ‘Kansas University Sl.: A New Generation’ in AS XXXVIII:3 174: To go to bed: Rack out.
[US]G. Underwood ‘Razorback Sl.’ in AS L:1/2 64: I’m going to go to my room and rack out.
[US]R. Price Breaks 117: Usually they left their door ajar when they racked out.
[US]Eble Campus Sl. Oct.
[US]J. Ellroy ‘Jungletown Jihad’ in Destination: Morgue! (2004) 375: Rape-os come out comatose and rack out too ratched to rape.