...Bananas

[Jonathon Green]

Thus 1970s UK 'bananas', corrupt policemen, because 'they're 'yellow, bent
[i.e. corrupt] and hang around in bunches'. There are other negative puns on
banana, e.g. the term for an Asian who has adopted Western values and is
'yellow on the otuside and white within' (a la 'apple' and 'oreo'). The
exception is 1950s Australia's 'banana', a one-pound note which is,
apparntly 'sweet and acceptable'.

Jonathon Green