Apart from the fact that many of us monkey around with them , not very much at all!
The monkey wrench got its name thanks to a mistranslation.
The tool was invented early in this century by Englishman Charles Moncke, who called it an "adjustable spanner." When the tool was imported to the United States, it was supposed to be called the "Moncke Wrench." However, we wrote the name the way it sounded, not the way it was really spelled, and it became a monkey wrench.
The tool inspired to expressions. "The first is "to monkey with," which means to try and fix. The second is "throw a monkey wrench into the works," meaning you try and fix something, but somehow make it worse.
Oh and there is no such thing as left-handed monkey wrench.
