I'm 32 and a mother of 4, and 'potty' humor still cracks me up!
However, I was also shocked by Sam asking for a dagger and Gimli f*rting.
Both instances were uncharacteristic. Sam would never be ungrateful for what he had been given.
After winning back Erebor, I am sure Gloin was held to Noble statis (or more), therefore, Gimli would definitely know proper manners around Nobility and Royalty.
As far as the other humor, it didn't bother me too much. I hate to sound like a simpleton, but I think the movies would be boring if everything was exactly like the books (yes I read them and love them both). Sure some parts were too much and I agree with every instance that has been stated so far...short jokes, one liners, Gandalf beating the h*ll out of Denethor and so on. But on the flip side, I probably would go nuts if the movies were solely artistic. But where is that fine line that seamlessly blends the two? I certainly don't know, so therefore, hats off to Peter Jackson for doing the best he could and I say... IGNORANCE IS BLISS.