While researching a comment on the last entry, I found a site (in German) with a list of types of non-verbal communication in road traffic: Nonverbale Kommunikation im Straßenverkehr. They include five different ways of flashing your lights (Lichthupe, literally ‘light horn’), warning flasher (Warnblinker), foglamps (Nebelscheinwerfer), and indicator (Blinker).

However, they omit one signal I saw quite a lot of when I started driving again in Germany a couple of years ago – the middle finger (sometimes down to the elbow, with window open). There’s also tapping the forehead.

Another driving site gives information on driving during Fasching / Karneval. You mustn’t drive with a mask on.

bq. Besteht bei einem Unfall ein kausaler Zusammenhang mit dem Tragen der Maske, besteht wegen grober Fahrlässigkeit sogar der Verlust des Koskoschutzes.

bq. If there is an accident with a causal connection to the wearing of the mask, you may even lose your (comprehensive) insurance cover (I presume Kosko is a typo for Kasko, and not Kokos / coconut as I read it first).