Lyndie Loo, We laugh at ourselves for the same reasons. Check out the "You Know You're A Redneck If", travelling salesmen, Texas, Maine, etc. jokes. No offence taken. Then take a look at Spaw's Cletus, Paw and the Reg boys' adventures.
I was in a small restaurant in Sydney, alone and waiting for service. The waitress was totally frazzled by a pair of midwestern women who were being obnoxious(SP). Their latest complaint was that the flowers on their table were not fresh and this would never be tolerated back home in the states - voices that would etch glass. I smiled, handed her my flowers, took theirs, and got a menu. When the poor lady came to get my order, she said under her breath "Damn Americans! I hate them!" Then I gave my order - she was horrified at my accent and started to apologize. I laughed and said that I hated Americans like that too. I call it "Big Fish In A Little Pond" syndrome. Mrs. Murphy from nowhere USA is so thoroughly impressed by her own self importance (after all no one in her home town has ever gone beyond DisneyWorld) that she starts to believe her own hype.

It's too bad that American sitcoms make it around the world. They are to the average American what Benny Hill is the average Brit.