A fork of Rural Dictionary
Mr. Rawley, a prestigious educator from Imagine Schools says, "In reference to dime meaning 10 and dozen, 12, this phrase can be described as an event or phenomenon occurring 10 out of 12 times.
It's believed that "dime a dozen" originated in the 1800's when a hen was expected to yield at least 10 viable eggs out of 12 that are laid.
Something that is very common, and can be found easily. This is a US phrase, in the UK it is usually stated as "ten a penny".
Oh, being gay is so fashionable these days, they're a dime a dozen!
Severely misinterpreted exopression... the original was derived from an unfortunate situation in the 1920's, when a tired shop-keeper decided to take a nap while standing behind the counter. A customer came over to him, asking the price of the bisquits...when the shop-keeper wouldn't repond, the man nudged him, and the poor sleepy man mumbled "I'm-a-dozing". Unfortunately the customer heard "dime a dozen" and the shop-keeper lost some goos bisquits that day...mm...bisquits.