Benjamin Franklin designed the first official US penny, minted in 1787. It's now known as the "Fugio cent" (Latin: I fly). At the bottom of the penny was the message: "Mind Your Business." (The message "In God We Trust" didn't appear on a US coin until 1864.)
There's some debate as to Franklin's intended meaning of the message. Some believe his pronouncement was meant to be taken literally, as in "pay attention to your business matters." Other say that Franklin, given his fondness for word play that can be found in the hundreds of quotes attributed to him, also meant that people should refrain from sticking their noses into the personal affairs of others.
If Franklin were alive today and someone asked him what he really meant by "Mind Your Business," I have a feeling his answer would be a mischievous smile.