Carnival lasts from November 11 to Ash Wednesday???
Uh...officially, yes. But in practice, we won't run around in funny costumes and drink alcohol for that long. On November 11, there are some major events even the daily news report about. But the rest of the time until "Weiberfastnacht" (last thursday before Ash Wednesday) we won't be affected by carnival apart from going to the odd carnival session, where most male attendants wear a suit and a tie and their only "costume" is either a red paper-nose or a small, "funny" hat - quite ridiculous (women usually wear more innovative costumes), and you watch dancegroups ("Tanzmariechen") and carnival comedy. And usually, there aren't many carnival sessions during Chistmas time.
It's "Weiberfastnacht" when everything becomes very crazy and your normally introvert, quiet coworker suddenly starts to dance half-naked on the streets, loudly singing carnival songs. You are supposed to party until Ash Wednesday, with carnival monday being the main celebration day, though the older I get the less stamina I have for this, so now I usually go out only on thursday and monday, sometimes going to a carnival session on the weekend.
I have been told that companies from other parts of Germany sometimes have a hard time understanding why they aren't able to contact any supply companies from our region on carnival monday, and if they can, why the whole staff seems to be drunk.
Yes, all this is very strange, but it has to do with history. Our region had been occupied by the French, who gave us laws and a limited freedom of speech. When Napoleon had been defeated, Austria and Prussia wanted to install a more rigid system, which the people didn't want. They started to wear costumes mocking the Prussian military uniforms, and staged meetings mocking the Prussian/Austrian leadership.