As soon as the calendar turns, it's time to start scheming.

April 1st, most commonly known as April Fools' Day, is a day devoted to foolishness.

Over the years, there have been some pretty good pranks.

In 1957, those funny guys at the BBC ran a segment on a bumper crop of spaghetti in southern Switzerland.

Another April Fools' folly, in 1996, Taco Bell ran an ad saying the company had bought the Liberty Bell.

The national treasure would now be called the "Taco Liberty Bell."

On April 1st, everyone seems to get in on the fun.

But how did April Fools' Day get its name?

The most popular theory dates back to the 16th century.

France celebrated the New Year just like we do today, except on April 1st.

Then, in the late 1500's, Pope Gregory XIII ordered a new calendar that called for the new year to begin on January 1st.

It seems, some didn't get the memo and continued celebrating on April 1st.

Story goes, everyone else called them April fools and played tricks on them.

No joke.

So, why do they call it April Fools' Day?

Now you know.