Every Thursday, really! From ~18:00 usually until ~21:00. Non-members are welcome! Don't ask, just come!
It's a time when:
Chaostreffs may be themed, usually as part of an effort, such as Cleantreff on the last Thursday of the month.
Any member may schedule a topic, talk, showcase, an event or similar for Chaostreff, essentially taking the focus to their topic presented. Streaming/recording is encouraged (setup provided)!
See also: Wiki Home, Membership
Chaostreff name comes from Chaos Computer Club and German word treff meaning meeting.