Being Americans, we think we're pretty awesome. Across the globe, not everyone will agree with that sentiment, however. If you don't want to stick out like a sore thumb, try to avoid these stereotypical aspects of an average American traveler.
20. Not Understanding the Metric System
There are only three countries on the planet that don't use the Metric system, so unless you're in Myanmar or Liberia, you probably want to keep your degrees in celsius and your feet to yourself. England doesn't even use the English system anymore even though it's called the "English system." Learn what a meter is. It's not that hard.