cockamamie, adj. — Green’s Dictionary of Slang

cockamamie adj.

also cockamamy, kockamamey

[? decalcomania, a picture or design left on the skin as a ‘transfer’, from specially prepared paper, which is wetted and rubbed (popular c.1862–4). Rosten, The Joys of Yiddish (1968), suggests that the shift came because ‘on the Lower East Side...no one knew how to spell “decalcomania”’; thus note Kober, Thunder over the Bronx (1935): ‘Then there were the “cockamanies” — painted strips of paper which the kids applied to their wrists and rubbed with spit until the image was transferred to their hand’]

confused, ludicrous, fake, fraudulent, absurd.

[1931		New Yorker 24 Oct. 72: Then there were the ‘cockamanies’ — painted strips of paper which the kids applied to their wrists and rubbed with spit until the image was transferred to their hand].
1942		Kanin & Lardner Woman of the Year [film script] Don’t give them the cockamamie bar stock.
1956		D. Karp All Honorable Men 281: He may yet speak up for Joe Ness, but not for that cock-a-mamie Committee of yours.
1960		Time and Tide 24 Dec. 1599/2: ‘A square’, Nemo shouts [...] ‘he is a cockamamie type, he is a stale adventurer... He’s not in my world.’.
1963		in T.I. Rubin Sweet Daddy 31: That cochamamie cell mate of mine.
1968		K. Brasselle Cannibals 105: We could be spending time on important matters instead of trying to get him his cockamamey VP stripes.
1970		Atlantic Monthly Sept. 118: If there are some confining or irritating or cockamamy rules of the house [...] these should be explained in advance.
1975		L. Rosten Dear ‘Herm’ 203: I hope this isn’t another 1 of your cockamamy jokeroos!!
1979		E. Torres After Hours 222: Through some cockamamie appeal you’re back on the street.
1985		J. Wambaugh Secrets of Harry Bright (1986) 281: I was told by Paco that you guys have some cockamamy theory about Harry Bright and me smoking the Watson kid.
1987		T. Wolfe Bonfire of the Vanities 216: There are so many fucking ifs in this cockamamie story.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 231: Your cockamamie TV show hasn’t panned out so far.
1990		S. Morgan Homeboy 37: Didn’t the shvartze know the only suspicious person on board was himself in that cockamamy outfit?
1991		in J. Breslin Damon Runyon (1992) 400: ‘Cockamamy!’ he yelled at them the first day. ‘Do you know where it comes from? In the old days on the East Side, they used to take decals and slap them on their foreheads and run around. It was a thing they did. They said it was “decalomania.” Somebody couldn’t speak right and he called it “cockamania.” That’s where it comes from.’.
1995		Eble Campus Sl. Dec. 4: kockamamey – totally unbelievable, false: ‘He made up this kockamamey story’.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 90: Shvartze pimps. ‘Talent scouts.’ Cockamamie ‘producers.’.
2017		L.A. Times 3 Apr. 🌐 Trump’s cockamamie border wall.