Onions

[denis567]

Does anyone know how the expression 'he knows his onions' came to be.

[gen2]

http://www.phrases.or...know-your-onions.html

[Jumbuck]

Brewers gives an alternative to the C.T. Onions derivation and gives what it reckons is a more likely derivation that it's from rhyming slang 'onion rings' meaning 'things'.

[denis567]

Thanks a lot. I fancy the chap with the coins seems to be a sensible source

[scotman]

Cassell's SLang Dict. gives th US derivation from 1920s.