Just because people draw these kind of things doesn't mean they do it on an impulse. You're mixing real life with some made up anime. You say you know how American's act but do you see every guy acting on your so called "TAP THAT AZZ 2 THE MAX?"
People just like talking about stuff like that just because they can. It's an anime after all and made to be enjoyable for whoever wants to watch it. It's not harming anyone in the process.