dumb and a half

when someone so dumb says/does something that is just too stupid for even them and takes their stupidity to a new level

person 1: bro, what happened to your microwave?

person 2: it blew up, i left a fork in there and turned it on

person 1: WOW! your dumb and a half!

Dumb-half

(adj) Describes someone who hasn't earned the whole insult. See: a**half

P1)Brad is such a a**-half.
P2)A genuine dumb***.

P3)He's not even worth the whole insult. He's a dumb-half.