Dumbfuckers are also people who, since they annoy you, never leave you alone. They think that what they say and do is the exact right thing to do and that you are bitch because you don't do what they say.
Dumbfuckers are scum, lowlifes, snotty do-gooders, even your family or best friends. They can be anyone, even you.
Mike Tyson....need i say more on this, he is also a dumbfucker because he looks down on others and he gets caught doing all these horrible things.
Anyone who thinks that they are superior to other people, or who thinks that other people think they are better than others, when they know they aren't. That just makes you plain rude and insulting and a dumbfucker