Found this news article: The National Orgasm Day (NOD) is celebrated on November 18. The original day was started in Brazil, with a law passed by a local councilman, Arimateio Dantas, to celebrate it. It is celebrated there on August 8, but celebrated in other countries like the UK, Australia and the US on July 31st. Make sure your provide to your significant other more than a quick NOD observance -- do it multiple times!!
Coincidentally, I was released a couple days ago and I'm not currently locked up. I didn't know it was National Orgasm Day yesterday, but I certainly celebrated!