Green’s Dictionary of Slang

1. a thin person.

1889		‘Mark Twain’ Connecticut Yankee 500: Go it, slim Jim!
1900		Marshall W. [Major] Taylor Fastest Bicycle Rider in the World (1928) 146: He has a muscular development that is the envy of every slim-jim that sees him.
1955		‘Hal Ellson’ ‘I Didn’t See a Thing’ in Tell Them Nothing (1956) 133: This is a weird cat. A real Slim-Jim and he’s shaking.

2. in pl., long tapered trousers.

1956

L.H. Hornstein ‘Women’s Shorts and Pants’ in AS XXXI:4 307: FRONTIER PANTS, FIRESIDE PANTS, SLIM JIMS. Long pants, tapered so closely that they must be zipped at the ankles or must have slits.

3. (also Slim Jim tie) a narrow tie, fashionable in the 1950s.

1957		H. Simmons Corner Boy 22: He had [...] a large assortment of Slim Jim ties.
1971		N. Smith Gumshoe (1998) 60: Still wears a slim-jim, drainpipes and big suede shoes.
1981		C. Hope Separate Development 100: The top button lying snug under the fat Windsor knot of your Slim Jim tie.
1991		F. Mac Anna Last of the High Kings 149: He had on his best jeans, new white shirt, black slimjim tie.

4. (US Und.) a small, narrow crowbar used for break-ins; thus v. to use such a tool for a break-in.

1987		(con. 1970s) J. Pistone Donnie Brasco (2006) 26: He taught me how to get into a vehicle using a tool called a ‘slim jim’ that you slide down between the outer door panel and the glass.
1990		D. Heilbroner Rough Justice 13: Auto boosters breaking into cars on ill-lit side streets with slimjims and slaphammers.
2001		J. Stahl Plainclothes Naked (2002) 155: I’m talking about the slim jim slim jim, like you buy at Pep Boys, to get into your nice-ass car when you forget your keys.
2010		(con. 1973) C. Stella Johnny Porno 232: [He] crowded up close to the [car] door to hide his using the slim-jim [Ibid.] 248: The mechanic used a slim-jim to unlock the door.
2017		T. Pluck Bad Boy Boogie [ebook] A big screwdriver from Tony’s shop, a slim jim for car doors, duct tape [etc].
2021		T. Pluck Boy from County Hell 195: He slim-jimmed the Buick’s door and screwdrivered the ignition.

5. (US black) the penis.

1980

J.L. Gwaltney Drylongso 161: When my cousin first came up here he was used to that corn row quicky stuff, and he got together with this young lady and she told him that a lame dude with a boiled Slim Jim could raise twice as much hell as he could.