The term mainly used by people in the south, can be used in almost any situation, But if a southern person is angry the longer they lead on with sumbitch measures the amount of ass about to be whooped.
Redneck #1: Hey did you hear about that Sumbitch that chugged 12 beers in 1 minute?
Redneck #2: yeah that crazy Sumbitch drank my whole 12 pack.
a dumb sumbitch is usually an individual who dip lays the characteristics of a so called "red neck." This person will speak or act with no real realization of what they are saying or doing. The person does not think on the level of that of normal people. They will be seen doing ludicrous acts of stupidity. This person is likely to be named Kyle Hodgkinson.
That kid just chased a deer on the side of the road, he is such a DUMB SUMBITCH!!!