1. [1940s–60s] (orig. US black) to go to sleep.
2. [1950s+] (US, also rack in) to sleep; thus racked out adj., asleep.
3. [1950s+] (also rack with) to seduce a woman, to make love.
[1970s] a seducible female.
[1960s+] (US) to fall asleep, to go to bed.