1: An insult, usually used to express distain of an act thought to be stupid. (Possibly a modicifaction of the word "dummkopf" meaning "fool" in German.)
2: A man who is all brawn and no brain, primarily used for sex and heavy lifting.
1: "Why'd you have to go and shoot that guy ya' Dumb Cock!!!"
2: (Shirly) "What DO you see in brad? He is SOOO dull!"
(Ashley) "I know but he fucks like a pro... Yeah, he's my big Dumb Cock..."