Fasching started this week (11th minute of the 11th hour of the 11th day of the 11th month).
For Germans who live in Koln or Mainz, it's a big deal. If you live in other areas of Germany, it's lesser of a a deal. Small towns do celebrate to a minor degree.
Typically, it will be referred to as the 'foolish' season. In Mainz, they say they have five seasons (spring, summer, fall, winter, and fasching).
It will end on Ash Wednesday.....so it's a fair bit of time in this season.
The peaks are typically on 11 November, Rosenmontag (Rose Monday toward the end) and the last month.
What typically happens? Costumes and costume parties are a trend....you dress up for the parades and the parties. I'm not talking about marginal efforts here....there are people who will spend easily a thousand Euro for some costumes because of their status in the carnival season.
Drinking and partying will be hyped up. Beer, wines, and beverages will be poured in fair amounts. I won't say Germans drink to excess.....but they drink to within one step of excess. Being within the urban environment of Koln and Mainz.....that means no one is stupid to drive and they all use public transportation to get to and from the parade or party.
Dressing warm for the parades is another big deal. November is one of those periods when it rains and temperatures drop.
Satire, cynical poems, sarcastic jokes.....get brought up during the last month as various parties will occur around the city and supported by various clubs. If you wanted five star humor.....this would be the festive occasions to attend. Although for the big parties (700 people showing up), you'd have to get tickets five to ten years prior to the event (that's how much interest that people have in this).
You may end up at such a party-dinner and discover that the local clerk of the drug store in town.....actually is a comedian and for fifteen minutes.....does as good of a job as any TV comedian in the US.
There are clubs which have dozens of guys working during evening hours from November to February to ensure their party goes off without a hitch. There are probably 10,000 man-hours put into preparation for some of these parties.
Where this started? Well.....most people agree that it goes back to Roman celebrations (before the Christians came along), and was later adapted to some degree as a seasonal thing when the Roman brand of Catholic Church arrived in Germany. It was supposed to be some end of winter where spring was in the air.....you could say things that normally would get you in trouble with the authorities or the church......at least during this carnival season. Alcohol and fun figured into this event to a degree.
Generally being an American watching this unfold, I'd say that you have two versions of Germans. For most of the year.....Germans are version one.....which is ultra professional and lacking humor.
Then version two kicks in and Germans start to become witty, showing a little bit more humor, dressing a bit different and seeming just a bit more happy than normal.
I should note....one of the chief episodes that occurs on on Fastelabend or Schmutziger Donnerstag....is the day set for women to be mischievous. The historic thing that occurs is that women are allowed to cut the neckties of guys at work. So most guys.....the professional types who wear ties.....will pull out a really old and crappy tie.....wearing it on this day and expect someone (maybe the secretary) to cut the tie in the middle of the day. All is done in fun of course (so they will tell you).
The parades that occur? They will have fun themes, and some critical comments of political groups. Generally, Germans have some harsh opinions of various leaders....locally and nationally....so this is a time when you can make a float which has some commentary that would normally not be accepted. Having the Chancellor dressed up in a trampy outfit and looking like a trailer-park gal for a float decoration......would be acceptable.
If invited to a parade with Germans.....dress warm.....wear some type of costume.....and be prepared to travel via train to the parade.
If invited to a party-dinner? Wear a costume....be prepared for happy Germans.....and drink at a pace that is comfortable for you. If they seem overly happy and not normal? Don't worry....after Ash Wednesday, they will return to the normal grumpy German culture that you are used to.