Saturday, May the 4th is the day geocachers from around the world gather together at events, all at once, briefly.
No really, why?
Oh you want a real answer? OK fine... May 4th, or Star Wars Day (May the 4th be with you... get it? No? Dang, tough crowd) is the day for the 10th World Wide Flash Mob (WWFM).
A flash mob, in this case, is a geocaching event that lasts only 15 minutes (i.e. it happens in a flash). It is designed to be the anti-mega event (where thousands of cachers meet in one spot for an entire day). The idea is that you show up exactly at the specified time, form a (friendly) mob of people, do a fun activity for 15 minutes, then disperse just as quickly. It is a quirky but fun way to spend 15 minutes.
As of this writing there are 547 flash mob events planned on May 4th, in over 41 countries, so there is likely one being hosted near you. To get a list of all the events planned, check out this bookmark list. For a lot more information, the main WWFM site is here.
As a bonus, if you log a WWFM event you (yes you!) will receive a custom souvenir icon (pixels, yay!) for your geocaching.com profile.
So now you know all of the information about flash mobs, you have no excuse to not attend one (ok fine, you may have several excuses, but you can check 'I didn't know" off your list). Go find a WWFM right now and log a 'Will Attend' log, then on Saturday join (briefly) your fellow geocachers for a fun event that you will not forget (unless you develop amnesia - my recommendation is not to do that.)
Just remember, the "flash" in flash mob means quick, not... um... this: