Green’s Dictionary of Slang

thicko n.

a fool.

1989		Beano Comic Library No. 181 27: What a bunch of thickos.
1999		Guardian G2 23 Aug. 4: He was marketed as a professional thicko. But was he thick?
2006		D. Mitchell Black Swan Green 93: Gary Drake’s no thicko.
2016		in Guardian 30 June 🌐 People say that the working classes were thick and didn't understand the issues but actually the middle class Guardian types are the bunch of thicko’s [sic] who don’t understand how a referendum works.
2023		Twitter 17 Mar. 🌐 Anti-vaxx MP Andrew Bridgen admits Laurence Fox's 'anti-woke' group wrote speech for him [...] He’s too much of a ‘Thicko’ to have written himself.