Green’s Dictionary of Slang

1. of a wager, (losing) substantially.

1828

‘A Flat Enlightened’ Life in the West II 31: ‘I am only out a eouple of hundred. Lord K— lost deep’.

2. (US black, also deep-down) a general intensifier.

1976		A. Salkey Come Home, Malcolm Heartland 88: I was deep, real deep into Malcolm. Brother Malcolm was all, man.
1986		S. King It (1987) 41: Whoever writes these little homilies has got a case of the deep-down crazies.
1998		(con. 1960s) G. Washington Blood Brothers 82: The next patient looked like he had a bad case of leprosy or elephantitis. Whatever it was, he had a bad case of the deep uglies.
2001		G. Pelecanos Right As Rain 198: A young man [...] made a comment directed at Juana, saying how he’d like to ‘kick that shit deep’.
2008		R. Price Lush Life 27: Tristan could almost count the times he’d been this deep away from home .

3. (orig. US black gang) well-supplied with members, thus phr. roll deep, roll thick, to have a large number of individuals in one’s gang or (in other contexts) group; also used adj.

1988		NWA ‘Gangsta Gangsta’ 🎵 We decide to roll and we deep.
1991		L. Bing Do or Die (1992) 36: Crips, man — deep!
1993		(con. 1975) K. Scott Monster (1994) 10: ‘There they go!’ Lep said, spotting the gathering of about fifteen people. ‘Damn, they deep too.’.
1999		Dr Dre ‘Some L.A. Shit’ 🎵 We roll deep, smoke on weed drink and back heat / Requirements for survival each day -- in L.A.!
2007		B. Coleman Check the Technique 271: ‘They [i.e. the Mobb Deep rappers] used to roll pretty deep out there with all their boys, probably ten guys most of the time’.
2007		W.J. Cobb To the Break of Dawn 60: [T]he ranks were deep. Listen, Guru, and the crew he ran with [...] rolled thick, like a host of ghetto potentates with diplomatic immunity.
2012		‘Dutch’ ? (Pronounced Que) [ebook] They knew his crew was too deep to trying anything.
2012		M. Lacher On the Bro’d 207: [T]hings were different this time ’cause we didn’t have our deep crew.
2014		Stormzy ‘Shut Up’ 🎵 They roll deep, I roll squaddy / Got about 25 goons in my posse.

4. (US black gang) in number.

1993		K. Scott Monster (1994) 253: We’d pile into my car four deep.
1996		UGK ‘One Day’ 🎵 I remember bein eight deep off in Chucky crib.
2008		G. Pelecanos Way Home (2009) 222: A car, three deep, rolled up on him in while he was walking to his aunt’s house.