Sorry…saying “Kewl” and “Britcom” will expose you immediately.
My 2p (cents) - is “My God is that a nipple…it is a nipple and during my favourite violent sport too!!! Pass the phone, I’m phoning the Government, President, my lawyer,the FBI…won’t somebody think of the children…please!!!”
ok I’m done 
We all need to keep in mind that the OP asked for stereotypes, not truths, so no need to get offended. I’m Canadian and we’re generally looked at as pacifist, cottage-loving, beer swilling hockey brawlers. I hate that image (except the pacifism), but there you go. We’re probably also the worst stereotypers of Americans because of our own schizophrenic inferiority complex over our proximity to the huge culture next door and our adoption of so much Americanism.
In any case, this question reminds me of a hotel guest I once met when I worked at said hotel. He was the quintessential American sterotype. He was a big black guy (though I don’t think race is part of the stereotype, I just want anyone reading this to create a clear picture) with a huge smile. The striking thing was, however, that in place of one of his massive front teeth was an even more massive gold tooth with a star of Texas stamped in it (I’m guessing something like the Dallas Cowboys symbol). You could go blind off his smile. Not to be outdone, though, was his belt, a big leather number with a huge gold belt buckle with a map of the state of Texas stamped in it. I swear it was big enough to be topographic. He also had on snake skin (or alligator skin, I don’t know) cowboy boots that were really loud (in the visual sense), a very colourful cowboy-style shirt and jeans, and a big cowboy hat. And on his meaty hands and around his thick neck were enough carats of gold to cover Bush’s budget deficit. He was loud of speech and had a definite southern accent. And overall, he was a really nice guy, friendly and truly excited to be in Canada (though I got the impression it was more like a novelty for him than because he actually cared to be here, but so what?). Do I think he was a typical American? No, but he was a shining stereotype and it was fun to see.
I will say this though: from working in a hotel and meeting many, many Americans, the only genuine stereotype I think that applies to a majority of the ones I met (not saying this can be generalized to the whole population) is a decidedly loud and somewhat self-absorbed nature (very demanding of service and lacking good manners), and being a good tipper. Take of it what you will.
One thing that came up earlier in this thread is that Americans seem to be overly fond of foreign royalty.
This has always seemed a strange thing to me, I am British and quite a royalist by British standards (I lived in Windsor so couldn’t get away from the buggers) I appreciate what they do, and think they enhance the countries esteem in the world. But, I find Americans who are much more favourable to the British Monarchy than allmost anyone in UK. The effect of Princess Dianna’s death was a case in point, I think more Americans felt personally effected by it than Brittish did.
It is charming that Americans seem to feel for the British Monarchy, but more than a little strange to behold as a Brit in America.
That’s something I’ve always questioned the accuracy of. I’ve seen plenty of sit-com and movie characters who love it, but I’ve never met a real person who really gave a rat’s ass about British royalty. Most everyone I’ve talked to about it had an “And you’re special because…?” attitude. <shrug>