The weirdness of the German customs and habits depends upon the country from which the ‘foreigner’ comes from. In any case, here are some general points:

• Relaxed view on nudity: Germans do not express any surprise or shock when they see a completely naked person on TV or in a Garden. They tend to treat that as normal and think of that as ‘birth-suits.’ For example, one could observe a lot of nude people in Englischer Garten in München and also around many lakes. To a person from India or even the Americas, this is absolutely shocking. But I have to come to think of it as a better approach in assuaging sexual repression. The more you see, the more mundane it gets.
• Taking a Fußpils / wegbier : Okay, Germans drink on the streets quite a lot. They usually carry a beer for the way (Wegbier) just to keep themselves loaded. Plus, any Platz is a good place for a good drinking game : Flunkyball - Spielwiki (in German)
• Anti-patriotism: Most Germans do not feel patriotic towards Germany. Foreigners who come to Germany automatically assume that Germans are very patriotic given their past. It is exactly the opposite and it is exactly because of their past. Germans feel that patriotism and nationalism are the root cause for all the divisions that exist in this world. It will be very hard to spot a German flag hanging from any house unless it is a government building or it is football time. Germans are proud of not being proud.
• Behaviour of leftist associations: One could actually observe many Leftist and Anti-fascist houses. They are fiercely leftist and wouldn’t tolerate any opinion that is divergent from theirs. In general, most German people are left-leaning but the leftist associations that I am talking about are extreme. They sometimes attack/vandalise houses which hang German flags. They hate the entire idea of Germany and I really don’t know why. It has its flaws but it is an amazing country.
• German coldness: A lot of people think that Germans are cold and/or emotionally distant. At first, it seems so because Germans like to know people better before they could be friends. I think it is quite an honest approach. I’d prefer that rather than someone pretending to be my ‘friend’ while actually not. In Germany, if you make friends, it usually lasts for a very long time. Thus, they take some time to build a solid foundation rather than a shallow one.
• German honesty: The Germans are incredibly honest if asked for an opinion. They will make it clear and direct. For an English speaker, this may come off as very rude but Germans just cannot beat around the bush. I personally like their honesty but I have to admit that I have been taken by surprise by the way they worded it. However, that could be the case of direct translation.
• German humour: The culture associated with German humour is completely different from what one may observe with English language humour. The construction of sentences in German, with the frequent use of compound word constructions, means that German humour relies more on humorous ideas than on wordplay. German grammar sometimes allows one to reorder a sentence without changing its meaning.

this intends to say “This place is under video surveillance by the police to prevent crimes” but could also be interpreted as “This place is under video surveillance to prevent crimes by the police”

• Some other habits which may seem weird to foreigners (non-Europeans):
  • Drinking beer during lunchtime.
  • Going around on Father’s day / Christi Himmelfahrt with a carriage full of alcohol, drinking it and sharing it.
  • Eating potato with almost every meal.
  • Being very strict about traffic rules.
  • Looking directly in the eye while clinking glasses. (They insist on that!)
  • Getting nervous when they realise that they can’t be at least 10 mins in advance.
  • Not understanding English jokes very well (Duh! They speak German)
  • Being very meticulous in what they do, sometimes upto an unbearable point, and general dislike for multi-tasking.
  • Drinking Kohlensäure Wasser (bubbled water) all the time.
  • Mothers and fathers taking their children to Christmas market and getting drunk/tipsy in front of them.