To start as a disclaimer, this is all my opinion. However, many U.S. expats would gladly agree with my sentiments on some of the strange (to Americans) things that Sie Germans do. So, here we go!
1. Walking Sticks aren't just for old folks!
This one cracks me up. If you live in Germany for a little bit, you begin to notice that a lot of people use walking sticks...to walk around. They don't have to be hiking or climbing a mountain. No no, a simple walk through the woods or on a gravel road may warrant bringing along the beloved walking sticks. The name for this is Nordic Walking. I've asked around and I guess you get a better workout versus just walking. This is understandable for those of you with bad knees, injured ankles or other ailments. But for people with no issues I don't get why they don't just run. I guess some people would rather take their walking sticks out. Oh, and as the title says, this is a sport for all ages. I've seen so so many people in their 20's going on nordic walks. This, to me, is downright strange.
2. Staring is completely acceptable
There's not much to this one, people here stare, a LOT. If you come over here and don't immediately notice it, you're not American. The funniest part is that when someone is staring at you and you stare back at them, they don't look away. Oh no, they just continue to stare at you. If you did this in the states, especially at night, I don't think you would like the response you would get.
3. Sprechen Sie Englisch?...'A little'
This cracks me up. I find it very humbling that most people in Europe speak at least 2-3 languages. We are so far behind them in the states. Here, it's always funny when we ask if someone speaks English. About 99% of the time they do, but they almost always say 'A Little' then proceed to speak perfect English. I asked a friend here and she said German people in general do not like to mess up or look bad, so they'll say that as a disclaimer in case they mess up. So now, every time someone says 'a little' I can just assume they speak perfect English. Works like a charm.
4. Must Follow the Rules!
This is something we learned quickly, Germans have no problem telling you if you are doing something wrong. They like their rules over here. People here actually wait for the crosswalk sign to turn green, even when there are no cars around. My friends have said Germans will tell you if they think your kids aren't dressed appropriately or warmy enough.
5. Sunday is Quiet Day
On Sundays, it is illegal to mow your lawn. It is considered rude to ride your loud motorcycle. Basically, you shouldn't use any mechanical or electronic device that makes noise. If the walls are thin between you and your neighbors, they might ask that you don't do laundry on Sundays (which is when I do laundry). German's like their quiet time. I have a girlfriend whose neighbors want her quiet 100% of the time, and they let her know it too. I personally think they should make thicker walls.
6. When it Snows, bring out the shovel
Every person is responsible for sweeping/shoveling the area in front of their house or rowhouse. The reason is that if someone slips and falls in front of your door because there is snow, you are held liable. When I first moved here I thought this was a silly law, but after living here for a while I am starting to see why this makes sense. I cannot explain why it makes sense, but I am assuming my change in thought must mean I am becoming a 'local'. However, our neighbor's shovel snow while it's snowing, sweeping the walkway off and also when it stops snowing. I'm not that dedicated.
7. When it doesn't snow, bring out the Broom
Even living at a townhouse, our neighbors still expect us to sweep the area in front of our place. This includes falling leaves, dirt that accumulates, etc. I cannot tell you how many 80 year old women I've seen sweeping the sidewalks in front of their homes and the streets as well!
8. Germans like to get naked together
That's a bold statement, but is the only answer I can come up with so far. Germans have no qualms about baring all in front of each other. Be warned, if you go to a sauna or spa you may be asked to remove your clothing because it is forbidden!
9. People are outside, a lot!
Ok this is not strange, but it is different from the states (and sadly, it is getting strange to do). People here get outside, and a lot too. When it snows, all the kids are playing outside. When it doesn't snow, all the kids are playing outside. People walk everywhere or ride their bikes. I am so impressed at how many people were running and biking when it was sub-zero here a few weeks ago. I am equally, if not more, impressed at how many people still bike when there's a few inches of snow on the ground. These people are tough!
10. If it's cold, dress appropriately. Always!
Whenever I'm walking to the gym and wear the capri three quarter pants, I'm always waiting for someone to tell me I need longer pants. This happened a few times so far this winter. People come up and point to my bare calves and go on (in German) about how I need to cover my legs up. It cracks me up every time!