Don't forget: October 13th is Sweet Potato Day! (I bring this up because yesterday I ate a bunch of さつまいも.) This comes from a saying "more tasty than chestnuts," where in Japanese "more" can be written as "4" and "chestnuts" can be written as "9," so when you add them together you get 13. That's a convoluted reason if I ever heard one.
Apparently, today is Wink Day. This is taken from the fact that if you put the numbers 10 and 11 next to each other and flip them on their sides, they look like a pair of winking eyes. It is also Railroad Safety Day and Apple Day. (Other amusing days)