Kelsey’s nuts, n. — Green’s Dictionary of Slang

Kelsey’s nuts n.

[punning ref. to the US Kelsey Wheel Company, founded in 1910 to produce automobile wheels. The need for nuts and bolts to be exceptionally tight fitting to preclude wobbly wheels gave rise to the saying]

(US Und.) used alone to imply the best, the absolute; used in phr. below as a superlative to mean ‘extremely’, ‘the most’.

1969

B. Jackson Thief’s Primer 58: Kelsey’s nuts: Sam says: ‘The first time I heard this I was playing basketball at the YMCA in Corpus and a boy on the other team told me, “You are all as dead as Kelsey’s nuts.” It means you’re all locked up, all set. Say a guy calls you long distance and says, “Now I want you to come on up to Chicago, I’ve got Kelsey’s nuts up here,” that means that he’s got a safe that’s an absolute cinch. All you have to do is walk in and say hello, and it’ll give you its money. Kelsey’s nuts is absolute, the best in the world, a cinch, a mortal cinch, it’s already taken care of.’.

In phrases

cold as Kelsey’s nuts (adj.) (also colder than Kelsey’s ass, ...nuts)

extremely cold.

1968		K. Brasselle Cannibals 17: It was 6:30 p.m., and colder than Kelsey’s ass.
1981		L. Block Stab in the Dark 21: ‘It must be a pretty cold trail.’ ‘Colder’n Kelsey’s legendary nuts’.
2003		Salon.com 8 Jan. 🌐 [Samuel] Fuller, born in Worcester, Mass., and a member of the U.S. infantry, recalls ‘it was colder than Kelsey’s nuts.’.

dead as Kelsey’s nuts (adj.) (also deader than Kelsey’s nuts)

(US) very definitely dead, out of favour; lit. or fig.

1939		J. Weidman What’s In It For Me? 247: Right now your styles are deader than Kelsey’s nuts.
1971		T. Thackrey Thief 286: They had my bound promise to kill them deader than Kelsey’s nuts!
1981		H. Gould Fort Apache, The Bronx 225: Advancement in the department can’t be it because Sonny, you’re about as dead as Kelsey’s nuts as far as that goes.
2000		J. Riepe Politically Correct Cigar Smoking Ch. xxi: Another man who needed some help in getting support for social programs that were as dead as Kelsey’s nuts.
2002		in Chicago Sun-Times 17 Nov. 🌐 ‘I announced my office, told him I was the police, told him to put down the gun. He didn’t and I shot him. And that was the end of the story for him.’ Deader than Kelsey’s nuts.

safe as Kelsey (adj.)

extremely conservative.

1955

D. Maurer ‘Technical Argot of Pickpockets’ in Lang. of the Und. (1981) 251/1: SAFE AS KELSEY. adj.phr. Conservative, not inclined towards taking unnecessary risks. Euphemism for ‘safe as Kelsey’s nuts.’.

tight as Kelsey’s nuts (adj.) (also tighter than...)

1. (US Und.) extremely mean, stingy.

1980		Maledicta IV:2 (Winter) 224: Some UK [sic] name play, such as tight as Kelsey’s nuts (or O’Reilley’s balls) for ‘parsimonious, is of obscure origin’.
1996		J. Kennealy Conductor 250: Tighter than Kelsey’s nuts is old Joe. Keeps pretty much to himself.
1999–2004		UrbanDictionary.com 🌐 CLUSTERFIST an individual who is ‘tighter than Kelsey’s nuts’ when it comes to parting with a dollar; a parsimonious peckerhead.

2. absolutely limited, e.g. of time.

2003

P. McAllister Cosmonaut 364: Those people up there are on a time line tighter than Kelsey’s nuts. Near as we can estimate they’ve got no more than four hours’ oxygen.