A Stammtisch is the table at which regular customers meet. In Germany, it's common for groups of friends or people with common interest to get together on a regular basis. English terms that might encompass similar activities would be special interest group and bridge club. Stammtisch often gets directly translated as "regulars' table".
In Germany there are many, many Stammtische. Some are groups of friends that have been meeting since they were kids and some are people with a common interest such as a Motorrad Stammtisch ( motorcyle enthusiasts meeting ).
