Green’s Dictionary of Slang

skinpop v.

also pop, skin
[SE skin + pop v.1 (5a)]

1. (drugs) to inject a narcotic beneath the skin rather than directly into a vein; the effect of such an injection is less immediate and somewhat weaker; thus skin-popping n.

[US](con. 1948) G. Mandel Flee the Angry Strangers 272: Even Lukey, skin-popping now, had his route.
[US]‘William Lee’ Junkie (1966) 56: He only gave up and ‘skinned’ a shot after an agonizing half-hour of probing and poking.
[US] in T.I. Rubin Sweet Daddy 64: A good kid starts popping then main lining.
[US]C. Brown Manchild in the Promised Land (1969) 263: He said he would stop using drugs altogether rather than start skin-popping.
[US]Time 16 Mar. 17: All my friends were on heroin. I snorted a couple of times, skinned a lot, and after that I mained it.
[US]E. Torres Carlito’s Way 80: The kid was only sniffin’, not skin-poppin’.
[UK]D. Powis Signs of Crime 201: Skin pop, to Inject narcotic drug (heroin, for example) into the skin rather than into a vein [...].
[US](con. 1930s) Courtwright & Des Jarlais Addicts Who Survived 82: When I couldn’t get opium, I took heroin. I was skin popping. [Ibid.] 87: I started off skinning it [...] That was the middle of ’32. I started sniffing in ’31; by ’32 I was on the spike.
[Ire]P. Howard The Joy (2015) [ebook] He said why not skin pop for the first time, like stick it straight into the skin instead of a vein .
[US]Simon & Burns Corner (1998) 61: They wouldn’t sell to wide-eyed virgins looking to skin-pop for the first time.
[US]ONDCP Street Terms 19: Skin popping — Injecting drugs under the skin; to inject drugs on any part of the body without hitting a vein.

2. (drugs) the scar left from such an injection.

[US]Tennessean (Nashville, TN) 25 Mar. 7/4: I saw a gruesome collection of needle tracks, skin-pops and sores.