We wanted to wait till after April 1 to post this list so you didn't think we were joking about "National Deep Dish Pizza Day," but we assure you: we never kid about pizza. Without further delay, let's get to the holidays.

1. April 2: International Children's Book Day

Celebrated since 1967, this holiday takes place on Hans Christian Andersen's birthday. Each year, a different national section of the International Board on Books for Young People (which sponsors the holiday) chooses a theme as well as an author to write a message and an illustrator to design a poster. This year's theme is "Imagine Nations through Story."

2. April 5: National Deep Dish Pizza Day

See, we promised. This day marks the anniversary of the first Uno restaurant—which is credited with inventing deep dish pizza—to open outside the city of Chicago. The holiday is designed to celebrate the spread of Chicago's signature dish, so no matter how far you are from the Windy City, go ahead and get some deep dish pizza.

3. April 7: National Beer Day

Each year, April 7th marks the anniversary of the signing of the Cullen-Harrison Act, which went into effect in 1933 and allowed people to buy, sell and drink beer again—as long as it was less than 3.2% alcohol by weight. Cheers to no more Prohibition!

4. April 8: National Be Kind to Lawyers Day

Even if, unlike me, both your parents aren't lawyers.

5. April 10: National Siblings Day

Hannah Keyser

Shout out to Emelye, Benjamin and Samuel Keyser!

6. April 11: International "Louie Louie" Day

Wikimedia Commons

On the birthday of "Louie Louie" composer Richard Berry, we celebrate the song that has been recorded more times than any other rock song in history. We'll do our best to sing along.

7. April 14: Pathologists' Assistant Day

A day to honor the "physician extender [in your life] whose expertise lies in gross examination of surgical specimens as well as performing forensic and medicolegal autopsies." (Thanks, Wikipedia.)

8. and 9. April 15: National Take a Wild Guess Day & National That Sucks Day

Both perfectly-timed to coincide with tax day.

10. April 17: Nothing Like A Dame Day

Getty Images

Celebrate the stateliest ladies you know and cultivate your inner dame with a rousing rendition of the Oscar Hammerstein show tune.

11. April 19: National Hanging Out Day

Sadly, this is not a day to kick back and relax with some friends. Rather, it's a holiday encouraging people to hang out their laundry—and cut down on energy consumption by doing so.

12. April 21: National Bulldogs Are Beautiful Day

How could you not love that face?

13. April 22: National Jelly Bean Day

Perfectly timed to take advantage of post-Easter sales on this colorful candy.

14. April 26: National Go Birding Day

Build bird feeders, bring your binoculars for a walk in the woods or, if you live in the city, take a little extra time to notice all the pigeons.

15. April 30: International Jazz Day

The United Nations Educational, Scientific and Cultural Organization is responsible for this holiday, which celebrates its fourth edition this year. Schools, communities, and even government organizations around the world will host programs to highlight the diplomatic role of jazz in bringing people together.

For an even more exhaustive list of holidays, historical anniversaries and notable birthdays, check out Chase's Calendar of Events.

All images courtesy of ThinkStock unless otherwise noted.