Green’s Dictionary of Slang

lay back v.

also lay low, lay up

1. to have sexual intercourse.

[US](con. 1944) N. Mailer Naked and Dead 377: You ain’t gonna be layin’ up with no woman.
[UK]I, Mobster 21: They’ll do anything to get a shot. If it’s a woman, she’ll lay up with a dog.
[US]E. Folb Runnin’ Down Some Lines 153: Other expressions for intercourse – to lay up/back/low, to give it up.

2. (US black) to relax.

[US]Harper’s Mag. Nov. 33: They will ‘hang loose’ and ‘lay back’ and, so mellowed out, the last thing of which they wish to hear is heroism.
[US]E. Folb Runnin’ Down Some Lines 176: Else get you some pluck, jus’ lay back smokin’ a reefer, you trippin’.
[US]Dr Dre ‘Still D.R.E.’ [lyrics] Whether you’re cooling on a corner with your fly bitch / Laid back in the shack, play this track.

3. to do nothing specific, to pass time (e.g. in prison).

[US]V.E. Smith Jones Men 150: I’m just laying back hoping the snitch will get his ass over there.
[US]E. Folb Runnin’ Down Some Lines 244: lay back/low/up [...] 2. Do nothing in particular.
[US]S. Morgan Homeboy 167: You gonna lay up on state tittie [...] You better get used to its juice.

In phrases

lay (back) in the cut (v.) [cut n.1 (12a)] (US black)

1. to relax.

[US] ‘Duriella du Fontaine’ in D. Wepman et al. Life (1976) 49: I lay in the cut on Carmen’s big butt / And kept her on her knees all night.
[US]‘Touré’ Portable Promised Land (ms.) 159: We Words (My Favorite Things) [...] Lay it on me. Layin in the cut. Let’s get it on.
[US]Simon & Price ‘Moral Midgetry’ Wire ser. 3 ep. 8 [TV script] That’s an extra five Gs a month for just layin’ in the cut.
[US]Simon & Burns ‘–30–’ Wire ser. 5 ep. 10 [TV script] You could take a slice for just laying in the cut, man.

2. to lie in ambush, whether actually or fig.

[US]‘Master Pimp’ Pimp’s Rap 165: I needed a plan that would allow me to lay in the cut.
[US]J. Lerner You Got Nothing Coming 149: The Hunger be layin’ in the cut fo you — fo sho! Talkin’ ’bout peelin’ yo onion.
at UrbanDictionary.com Feb. 24 [Internet] To hang out in the background. ‘Shit dogg! You lay in the cut straight sittin’ in yo’ ass and gettin’ yo’ drink on and yo’ snack on, while we floss and fly this mofo all over this bitch.’.
[US]G. Hayward Corruption Officer [ebk] cap. 36: [I] look down to see old Smokey, a large German Shepherd, just laying under the desk in the cut with his tongue hanging out just a waiting to catch someone.