Ha!!! My sides hurt....
I just had to add one of my own.
One night while making supper, my fiance asked "what are we having as a side dish?" or something to that effect. I answered, "Potatoes" The t.v being quite loud he didn't hear me and yells "What!?" I couldn't resist, I walked into the room he was in and said " You know p-o-t-a-t-o-e-s, boil 'em, mash 'em stick 'em in a stew." We both broke out at that one.
I believe it was Sam who said this. I'm not quite sure if it was just in the movies or if it was in the books too.
I know the "You shall not pass" one has come up a few times. Oh yeah and I just love doing the part in the movie in Rivendel when Viggo says something like "you cannot wield it, noone can." his voice goes all squeaky and so unAragornish, it just makes me laugh.