In 1883 the U.S. Mint introduced the Liberty-head nickel, and the designer decided to leave the word "cents" off the back.  After all, it was clearly nickel color, so what could the "V" mean except five cents? But enterprising scoundrels realized it didn't have to stay nickel color, and they gold-plated it (the second row shows the plated nickel).  Because the nickel was new, few had seen it, so most believed the scoundrels when they said it was the new five-dollar gold piece.

The Mint immediately saw the error of its ways, and before the year was out, they changed the back to include the necessary word "CENTS" (see bottom row).  It stayed that way until it was replaced by the Jefferson nickel in 1937.