Things in the US these days are just a little strange, or so it seems to me. I suggest that we put a sign (the same language as displayed to right) in every port of entry to the country. 

Take your pictures, enjoy the scenery, the ethnic food isn’t all that bad. But save the laughter for when you’re alone or back home.
I’m not saying that we don’t deserve to be laughed at. It’s simply rude to do it in person.