Here is a collection of silly, strange and obscure unofficial holidays celebrated in December. Links in boldface are featured on Worldwide Weird Holidays.
December 1
Eat a Red Apple Day
International Sweater Vestival – 2017
Civil Air Patrol Day
Day Without Art
World AIDS Day
December 2
Rockefeller Center Christmas Tree Lighting – 2015
Business of Popping Corn Day
International Day for the Abolition of Slavery
National Fritters Day
National Mutt Day
Play Basketball Day
Safety Razor Day
Special Education Day
December 3
Chester Greenwood Day – 2016 – 1st Saturday
Make a Gift Day
International Day of Persons with Disabilities
National Apple Pie Day
National Green Bean Casserole Day
National Roof-Over-Your-Head Day
SKYWARN Recognition Day
December 4
Santa’s List Day
Extraordinary Work Team Recognition Day
National Cookie Day
National Dice Day
National Kitten Day
Wear Brown Shoes Day
December 5
Krampus
International Ninja Day
International Volunteer Day
National Communicate with Your Kids Day
National Commute with Your Baby Day
National Day of Solidarity
National Sachertorte Day
Repeal Day
December 6
Microwave Oven Day
Mitten Tree Day
National Miners Day
National Gazpacho Day
National Pawnbrokers Day
Put On Your Own Shoes Day
St. Nicholas Day
December 7
National Cotton Candy Day
International Civil Aviation Day
National Letter Writing Day
National Pearl Harbor Remembrance
Special Kids Day
December 8
Tió de Nadal begins
Take It in the Ear Day
National Brownie Day
National Christmas Tree Day
Pretend to be a Time Traveler Day
December 9
Cremation Day
Official Lost and Found Day – 2016 – 2nd Friday
Christmas Card Day
International Anti-Corruption Day
National Pastry Day
National Salesperson’s Day
Weary Willie Day
World Techno Day
December 10
Dewey Decimal Day
Festival for the Souls of Dead Whales Day
Human Rights Day
National Lager Day
Nobel Prize Day
December 11
Worldwide Candle Lighting – 2016 – 2nd Sunday
Holiday Food Drive for Needy Animals Day
International Mountain Day
National Noodle Ring Day
December 12
Poinsettia Day
Festival of Unmentionable Thoughts
Gingerbread House Day
National 12-Hour Fresh Breath Day
National Ambrosia Day
National Ding-a-Ling Day
December 13
National Day of the Horse
Ice Cream Day
National Cocoa Day
National Violins Day
December 14
Monkey Day
National Bouillabaisse Day
December 15
Cat Herders’ Day
National Regifting Day – 2016 – 3rd Thursday
Bill of Rights Day
National Lemon Cupcake Day
Boston Tea Party
National Ugly Christmas Sweater Day – 2016 – 3rd Friday
Barbie and Barney Backlash Day
National Chocolate Covered Anything Day
Stupid Toy Day
Underdog Day – 2016 – 3rd Friday
December 17
Wright Brothers Day
National Maple Syrup Day
Pan American Aviation Day
December 18
Bake Cookies Day
Flake Appreciation Day
Free Shipping Day
International Migrants Day
National Ham Salad Day
National Roast Suckling Pig Day
National Wear a Plunger on Your Head Day
December 19
National Oatmeal Muffin Day
Holly Day
Look for an Evergreen Day
National Hard Candy Day
December 20
Mudd Day
Cathode-Ray Tube Day
Dot Your I’s Day
Games Day
Go Caroling Day
International Human Solidarity Day
National Sangria Day
Sacagawea Day
December 21
Forefathers’ Day
Anne and Samantha Day
Crossword Puzzle Day
Humbug Day
National Flashlight Day
National French Fried Shrimp Day
National Kiwi Fruit Day
National Look At The Bright Side Day
Phileas Fogg Win a Wager Day
Winter Solstice – 2016 – longest day of year
Yule
December 22
National Cookie Exchange Day
National Date Nut Bread Day
December 23
Festivus
HumanLight
National Pfeffernuesse Day
National Roots Day
December 24
National Eggnog Day
Super Saturday – 2016 – last Saturday before Christmas
Last-Minute Shopper’s Day
December 25
A’phabet Day/No-L Day
National Pumpkin Pie Day
December 26
National Whiner’s Day
Boxing Day
Kwanzaa
National Candy Cane Day
National Thank You Note Day
December 27
National Fruitcake Day
Make Cut Out Snowflakes Day
Visit the Zoo Day
December 28
Pledge of Allegiance Day
Call a Friend Day
National Card Playing Day
National Chocolate Candy Day
December 29
National Pepper Pot Day
Tick Tock Day
December 30
National Bicarbonate of Soda Day
Bacon Day
Festival of Enormous Changes at the Last Minute
December 31
Banished Words List Day 2016
Banished Words List Day 2015
Make Up Your Mind Day
National Champagne Day
New Year’s Eve