UK, 1877—an onion-seller from Brittany who sold onions door-to-door around the coasts of Britain—used with modifying word, ‘Johnny’ designates a person of the type, profession, etc., specified
USA, 1925—With, of course, a pun on ‘pee’, meaning ‘to urinate’, the jocular phrase ‘silent like (the) ‘p’ in swimming’ is used when exposing a difficulty in pronunciation.
American English, 1965—signification: to be kept in a state of ignorance and told nonsense—in use a few years later in Australian English and British English
USA—1853 to kidnap for service aboard ship—seems to have originated in San Francisco—refers to Shanghai in China, the ships in question going to eastern Asia
Decided by the Académie française, the erroneous spelling ‘oignon’ (= ‘onion’) has become a symbol of prejudiced people, ignorant of the history of their own language.
UK, 1882—to remain motionless and quiet; to keep a low profile—probably from ‘dog’ and suffix ‘-o’, with allusion to the characteristically light sleep of a dog