We buy and sell a wide variety of unfamiliar-sounding currencies from across the world: taka, reals, lev, colons and ringgits to name a few; but these are all real, official names of currencies in circulation today.
In England, pre-decimal currency had it's own slag names. The shilling, equal to today's 5p, was known as the 'Bob' and the half-shilling or sixpence was known as a 'tanner' or a 'tilbury'. The 5 shilling piece (25p today) was known as a 'crown' or '5-bob' and it's sister the 'half-crown' of which one or two bawdy songs were written and you have to be of a certain age to have sung them!
Some slang words for British banknotes have endured and post-decimal we now have a 'ten bob bit' (50p), 'nugget' (£1), a 'melvin' (£5), a 'pavarotti' or 'browny' (£10), a 'score' (£20), a 'pony' (£25), a 'ton' or 'century' (£100), a 'monkey' (£500) and loads of names for £1000 including 'grand', 'bag', 'grubby hand', 'bucket', and a 'large'!
Canadian dollars
$1 coin = 'loonie', $2 coin = 'toonie', $5 bill ='fin', or 'half-sawbuck', $10 bill = 'ten-spot' or 'sawbuck' and $100 bill = 'c-note'.
South African rand
Mainly derived from township slang we have R10 note = 'tiger', R20 = 'croc', R50 = '5 tiger' or 'pinkie' or 'jacket', R100 = 'clipper' and R1000 = 'grande' or 'stene' and R1m = 'bar'.
US dollars
The country that gave us dimes, nickels and quarters also name a $5 bill a 'fin', 'fiver' or 'five-spot', the $10 bill is a 'sawbuck' or 'ten-spot' or 'hamilton, $20 the 'jackson' or 'dub'. The $50 dollar bill is called a 'frog', and $100 a 'franklin' or 'c-note' and $1000 a 'grand', 'stack' or a 'large'.
And by the way, a 'saucepan' was the slang term for the old Aussie pound, after the British 'saucepan lid' (quid). You learn something new every day!