The ultimate idiot. Not only used when someone does something ultimately retarted, but also when you can't stop shaking your head and uttering "meh" as in, this dumb @$^ fool!
Jenni: <breaks out in a stride into a building with no electricity>
Vickie: You dumb *&% , aint no power n dere plus it"s hott! DUM-MEEEEEEH!