Get together with fellow cachers to celebrate the Fourth Square Root Day of this Century! Ron Gordon, a Redwood City, California high school teacher, created the first Square Root Day for September 9, 1981 (9/9/81), and they've been promoted as an informal holiday ever since.
Math matters to geocachers (that GPS is a just one example of how we use applied mathematics to have fun in our game!) so it's a natural we'd notice how special Square Root Days are on the calendar. There's only nine of these days per century! The number of years between consecutive Square Root Days in a century are consecutive odd numbers: 3, 5, 7, 9, 11, 13, 15, 17. This illustrates the fact that every odd number is the difference of two consecutive squares. So the next time you see an odd number, know it's because a couple of consecutive squares made a difference... 
Stammtisch: Loosely translated from German meaning a "regular get-together." Literally speaking, the word Stammtisch is a table in a bar or restaurant which is reserved for the same guests at the same time every day or every week. There is usually a sign on the table saying "Stammtisch." If you don't belong to this table, don't attempt to sit there! In the most traditional German beer halls there is a large brass plaque above the table with the word Stammtisch printed on it in bold lettering.
There can be all kinds of Stammtisch. There are those simply for friends to drink together. Or those for specific interest groups - say a "Philosophy Discussion Stammtisch" or a "Stamp Collectors Stammtisch". In our case, I hope to start a "Geocaching Stammtisch."
This event continues a new Alaskan caching tradition of cachers informally, but regularly, getting together to swap stories, tips, and tricks over a meal or beverage.