1. In our small town, if you pay money to go to the public indoor pool, the men must wear a speedo. No shorts allowed. The women must also wear a close-fitting garment with nothing hanging off like a skirt, t-shirt, or shorts. No exceptions for being raised American!
2. We don't have any apartment numbers in our building, or any I've seen. Our last name is on our door, on the buzzer at the entrance, and on the mail box outside of the building.
3. There is no school on Wednesdays for children middle school and younger. It's like a Saturday. There is a half day of school on Saturdays, about half the time.
4. No one has the same name in a certain region in France (or so I'm told). You can not name your child after his father. There are no "juniors" here. And it causes problems if you named your son after yourself and then you moved here. (Thankfully, we did not do that but we know people who did. They regret it.)
5. Cursive is taught in pre-school. Every sign or advertisement (that I've seen) that is hand-written, is in cursive.
6. However, last names are written in all caps, like this: John SMITH or SMITH, John. That way you always know which name is the pre-nom and which is the nom.
7. I also find it odd that in an almost completely secular society like France, with a few exceptions (bakeries and some restaurants), stores are all closed on Sundays.
8. People point at things (anything) with their middle finger (you know the one). When our children started doing this we corrected them, until we noticed that everyone at their school and our church did the same thing. Now we've just let it go.
9. There is a two hour lunch break at school from about 11:30-1:30 p.m. Most businesses are closed for at least 2 hours around the same time.
10. When you walk into an apartment building and walk up a half flight of stairs to the first floor that has apartments, you're on the ground floor. If you then walk up a full flight of stairs to the second floor with apartments, you're now on the first floor.
I'm sure there are more. Feel free to add your own in the comments.