They get publicly drunk.
It’s obvious—Americans like to have a good time. Perhaps it’s having too much of a good time they have an issue with. Americans are always looking for an excuse to party and, understandably, spending time in a foreign country is something that needs celebrating. Back home, heavy public drinking is the norm while drinking at home is somewhat taboo.
Besides, the drinking age in the United States is 21 and much, much lower in most other countries, if they have them at all. It’s no surprise American drinking habits are so much more extreme—they’re making up for lost time.