Though I would love to take the credit its a very old slang expression for money. I am a voracious reader and movie watcher so I pick up tons of useless information, cliches and the like.See here:
Quote:
The 1920s and 1930s were particularly rich in American slang terms for money, some of which are still in use today. Some terms referred to money’s use in purchasing food: bacon (as in bring home), bread, dough, and so on. (One term for counterfeit money was sourdough.) Other terms referred to the green colour of American bills: cabbage, lettuce, kale, folding green, long green.
Other slang terms for a dollar include ace, bean (as in bean counter), boffo (abbreviation of box office, referring to money collected at theatres), bone, buck, bullet, case note, clam, coconut, fish, frogskin, lizard, peso, rock, scrip, simoleon, and yellowback.
The heavy dollar coin was once known as an iron man, plug, sinker, or wagon wheel.
I am a voracious reader and movie watcher so I pick up tons of useless information, cliches and the like.
If you want more money slang here ya go: http://www.fun-with-words.com/money_words.html