+2
Ah. Well, I can't say I agree. Crank isn't even a comedy, and Grandma's Boy made a grand total of $6 million domestically, so it can't have struck too close to the heart of American comedic sensibilities.
I think any attempt to boil American humor down to a film or two (though I'm dubious of any such attempt to begin with) would have to pick something that's at least quite popular/successful. Perhaps The Hangover, though that's just among very recent films. If you go with things like adjusted box office, you're looking at stuff like Beverly Hills Cop, the Austin Powers series, Home Alone, etc. Pretty varied stuff; only Austin Powers is raunchy, and just as often it's more cheeky innuendo or Bond-skewering than anything else.
But really, it depends on who you ask, and what you're asking. In terms of modern box office, it might be Adam Sandler and Will Ferrell (usually). In terms of people who fancy themselves movie lovers, it's Dr. Strangelove and maybe Groundhog Day. If we're comparing the best comedy in one country to another, I don't think Americans have a thing to be ashamed of. If we're just going by the degree of public consumption, then I can buy that there's a bit more acceptance of raunchiness, but I think it's mostly relegated to rentals and small pockets of people. The one big, raunchy, runaway hit that comes to mind is There's Something About Mary.
It's a tough question to answer in part because, in America, we still see the stupid comedies like Grandma's Boy even if we're not interested in them, whereas if there's some poorly-received low-brow European comedy, we probably won't ever hear about it. Unless we dig quite deep into foreign comedies, we're generally only going to see the really popular stuff from across the pond, which is bound to exclude the really bad stuff.