It is interesting what does and does not make it over the Atlantic and what has been filtered out for one reason or another. I've talked about the one way language barrier before (caused by American movies and TV showing all over the world, the reverse not being true so I don't know a lot of British slang.) But there is a lot of stuff I can talk about for American culture that everyone understands until there is just some hole and my joke will deadpan. Then I get the look. Of course, if I'm not sure if they have heard of something and they have I also get that same look.
I was watching TV with some of the British students and they had never heard of the movie "Ferris Bueller's Day Off" but have heard of the band "Save Ferris". (They also were truly disturbed when they saw Cameron in the movie saying "Hey batter, batter, batter, swing batter". I had to explain that was normal to say at a Baseball game and was not Turrets.)
Besides the odd movie that has slipped through I have noticed that the coverage of American culture is a recent phenomenon so shows like Gilligan island got a blank stare from everyone. Since they get the shows but not the commercials I find that references I make to commercials leave the biggest holes. I was trying to explain the Pillsbury dough boy, which to me, makes perfect cultural sense. That is until I catch myself saying that poking a little white thing and making him laugh will help sell pastries.