Green’s Dictionary of Slang

not worth a pinch of... phr.

also ...of bulldust, ...(cat’s) piss, ...cold shit, ...coonshit, ...owl dung, ...poop, ...shit
[shit n. (1a)]

(Can.) worthless, useless.

[Aus]Age (Melbourne) 1 Mar. 2/3: The Marijuana Party [...] ‘The only party worth a pinch of shit’.
[UK]Barltrop & Wolveridge Muvver Tongue 41: ‘Not worth a pinch of cold shit’ means of no use to man or beast.
D.L. Ouren Pope County Trib. 21 Sept. [Internet] A man often dismissed in popular Civil War histories (including the recent PBS series) as a swaggering braggart, a man ‘not worth a pinch of owl dung’.
[Aus]Smith & Noble Neddy (1998) 264: The two cops witnessed it formally to make it look good, but really, it wasn’t worth a pinch of shit.
[Aus]G. Seal Lingo 125: [Piss] may be applied in terms indicating contempt, such as you wouldn’t piss on him if he was on fire and not worth a pinch of piss or, more colourfully, not worth a pinch of cat’s piss.
Paul port-sparc list NetBSD Mailing Lists 11 Dec. [Internet] PS remember the power on self test of RAM is not worth a pinch of bulldust.
T. Greene Bad Date 35: These kids are made to feel their life’s not worth a pinch of coonshit .
‘Frodo Baggins’ User Opinions on Read Plus CNET Download.com 25 Aug. [Internet] ‘Not worth a pinch of poop!’ It claims to be free but it isn’t free.
[Aus]Jennifer ‘Aus. Sl. Phrases’ Jennifer’s Jibberish [Internet] Not worth a pinch .......... worthless.