The Name for a person who has been infected with the "Dee" Gene. The dee gene causes a rare form of mental retardation simply known as DEE. Because of its hereditary nature, whole families (known as LOS DEES/DOUS) have been known to carry this gene. Besides being hereditary, it has been proven that habitual exposure to people carrying the gene can lead to infection. El Dou, also, can be used as an interchanable synonym for complete and utter retardation.
Seth was being inchorent, saying things that bordered on non-sensical and retarded, so Jones screamed "EL DOU"