I created my own holiday a few years back which I've observed every year with friends since its inception... Nacho Friday.

It occurs on the 2nd Friday in July, you have to drink copious amounts of Tequila, consume lots of nachos and wear a novelty oversized sombrero all day.

Anyway, us Aussies have to celebrate Pi day next month (kinda) - 31/4 as today is 14/3 for us.

Although it seems wikipedia has an interesting article on the number 143, it can be created by adding up 2 different sets of consecutive prime numbers, which I found interesting.