By the way, "الصعايده" "Saeydah" in Egypt, targeted with the majority of jokes, are not really dumb. Most of the egyptian scientists and a lot of business men are Saeydah. Some notable saeydah are:
Jamal Abdelnasser (President who led the coup against King Farouk), Hosni Mubarak (current president of Egypt), Susan Mubarak (his wife), Prof. Majdy Yaacub (one of the biggest surgeons in the world), Taha Hussain (one of the most influential writers and intellectuals), Huda Shaarawi ( famous Egyptian feminist leader and nationalist), Abdulhakeem Amer (Egyptian military general and political leader), Jihan Assadat (the wife of the assassinated president of Egypt Anwar Assadat), Abbas el-Akkad (famous Egyptian writer) and many more.
I'm sure many egyptians agree with me. Same goes to "الحوطة" "hotah" in Saudi Arabia. They aren't that stupid, Lots of 'em are scientists and big business men. I know it's just humor, but maybe it's jealousy that started these kinda jokes? I don't know!
Just wanted to get this off my chest