Unlike son of a bitch which is in reference to ones canine mother, son of a motherfucker is in reference to ones father that it is assumed was a motherfucker.
Can also be used as a curse when frustrated or infuriated by something.
Ask Doug?! Why, I wouldn't trust that son of a motherfucker as far as I could throw him.
What is wrong with this goddamn remote?! Son of a motherfucker!
After spilling your cereal all over the floor:
Oh, man. Son of a motherfucker! Shit!
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