Well, those Internet forums. Anyone can come from anywhere to any purely American forum and write whatever is in his/her mind. Some of those foreigners are intelligence agents, no doubt, it's proven (I'm not joking). What's the law - maybe Americans are not careful enough?
American forums as American soil?
I could go to Niamey, Niger, visit an Internet cafe there and spread my gossip from Africa. That's how small the world is. Every computer has the same Internet. Few things are available as limited to the US. Some YouTube clips, and what else?
I read American papers, visit American forums, watch American videos, watch clips from Fox or ABC - all on a computer.
I know that you believe that there's a deeper layer of Americanism which no one understands. Well, if someone doesn't have a childhood in the US, those things just don't seep in.
And they are: TV cartoons, comic books, baseball, American football.
Well, that sphere is getting smaller and smaller.
Marvel comics are published in Poland. Rules of football and baseball are easy to find on the Internet. Walt Disney cartoon movies have been known here for ages. The Muppet Show was shown in Communist TV in the 1980s, and Battle of the Planets, and Planet of the Apes. However, few people had color TVs back then.
An average Pole has seen hundreds of American movies, of all kinds, our TV shows American films in a "scientific" manner. I mean, if you have just the 7 or 10 free channels, you can make a list of well-known American movies and after 3 or 4 years you will be 80% done.