Word for the Wise October 26, 2006 Broadcast Topic: Two bits
A regular listener wrote us when he suspected he and his wife had been using a phrase that no longer had currency. It seems that when his grandsons asked why he and grandma were using the term two-bit to mean "trifling," his memory came up short. (来源：英语聊天室 http://chat.EnglishCN.com)
Our correspondent knew two bits didn’t add up to much, but he couldn’t quite remember why. We’ll help piece together the tale. First, the tale of two bits predates him and his wife by a few generations. Our second bit of information concerns coins of the realm—specifically, the English threepence, a coin worth three pennies—that was once known by the slang term bit. That bit of slang carried over to the New World, where bit was applied to the old Mexican real worth—no, not three pennies, and not sixpence either. The Mexican real was worth no less (and no more) than twelve and a half cents.
Two bits, then, added up to one quarter of a dollar, or twenty-five cents. Back in the early seventeen hundreds, two bits was nothing to sneeze at, but by the eighteen-hundreds, two-bit had also become a (hyphenated) adjective meaning "cheap or trivial of its kind; petty; small-time."