Since 2000, October 22 has marked International Caps Lock Day, a day of festivities, fond recollections of departed television pitchman Billy Mays, and, of course, leaving your computer on non-stop, permanent CAPS LOCK. Repeated typos optional. Note that June 28th is also an International Caps Lock Day of sorts, since it marks the date that Mays died in 2009; however, October 22 has the longer history of commemorating caps lock appreciation. Only on the Internet.

The Next Web dug up a semi-serious (!) explanation for the day, as laid out by founder Derek Arnold some time ago:

International Caps Lock Day is in fact a testament to the small mindedness of certain Western individuals: the majority of the world’s population writes in scripts which have no concept of letter casing. Therefore it is advised to laugh at anyone who invokes this day as an excuse to dismiss local typographical conventions: they are simply making an ass out of themselves.

Of course, in real life, capitalizing everything may annoy the crap out of everybody, so use caution. Unless you’re this guy. (Language NSFW)

If you’re lazy about capitalization, you can always run text of varied cases through this case-converting script and marvel as your lollygagging lowercases convert into cromulent capitals. Source  Geekosystem