Does anyone know about the "Ehs" and the "You-Alls?"

In Afghanada, CBC Radio's excellent drama about Canadian soldiers fighting in Kandahar province, the Canadians call the Americans "You-Alls" and the Americans call the Canadians "Ehs."  Does anyone know if these slang phrases exist, or whether it is just inspired invention?

Image:  Some "Ehs" in Kandahar, some years back.