The upcoming saturday (Dez. 3rd) is Global Day of Coderetreat. It’s a world-wide event celebrating passion and software craftsmanship. 

Coderetreat is a day-long, intensive practice event, focusing on the fundamentals of software development and design.

You can find more information about the Coderetreat format and the event on the official website. For cologne all the information is on a github wiki and you should follow the office twitter account for updates.