It is funny how there is a dichotomy here. On one hand American culture is spread through movies and TV shows so it is not considered foreign to anyone here. So things like the pizza sign make sense since it is really American Pizza and not Italian that they are serving
Some people are scared to visit the U.S. since they think it is dangerous enough that everyone needs to buy guns to defend themselves because there is no law outside the law at the barrel of a gun (yes, they really thought this). I've had to explain that, no, it's not because it's dangerous that everyone arms themselves. That people feel strongly about being able to own guns because it is in the Constitution and they feel that people are trying to take the right away from them, so they buy guns to show they can buy guns (and to have them should the gun laws become stricter). The last time that I was here I couldn't convince an old man that it was the conservative viewpoint in the USA that wanted to defended the right to keep guns. According to him "The USA will not be a civilized country until they can get rid of the idea that they need for so many guns." I really don't know how to explain this one to people around here because on one hand they all see American movies where, of course, everyone is shooting at everyone else.
The other big one is religion. Of course Europe has a much lower level of people that identify themselves as religious so signs like the following are everywhere:
The other stereotype that I have heard from a lot of the other students is that Americans don't know geography. While there is a good chance that Americans might have problems naming where Latvia and Moldova (Those are the two I got messed up on.) I have already been asked how many states there are (people here have a hard time deciding between 50 or 51) and most don't know which states are where or which countries are in South America so I am chalking that one up to unfamiliarity with the continent you are not living on.
There are good stereotypes too. Apparently every American that travels abroad are the friendliest people there are. So other traveling Americans, thank you for making it easier for me. That being said if you don't want to stick out like an American tourist according to the locals here, don't wear tennis shoes (or as they are called here "trainers") and don't wear any T-shirts when visiting. (The main reasons why I personally don't like looking like a tourist is a lower chance of being pick-pocketed and getting hassled less by people trying to sell tours.) But hey, if you want wear a t-shirt with white basketball shoes to show your patriotism then have fun.