Tomorrow is Pi Day because in the way Americans write dates March 14 becomes 3.14 which are the first three numbers of the number Pi, if you get what I mean. So mathematicians and bakers around the world will be celebrating tomorrow as they do every year.
Some people take this way too seriously, like this Canadian school teacher Mike Pretli "who shattered a 34-year-old Canadian record of 4,096 decimals for correctly reciting from memory the sequence of Pi. Pretli ended what he termed “the mental marathon” at 6,320 decimals." This guy spent a year of his life memorizing 10 digit numbers and their sequence. And if you think that is a little weird you should know that the US record is 15,340, and the world record, 67,890, set by Lu Chao of China.
And if you think I jest may I refer you to the official Pi Day website.