Porque tem um verbete sobre a palavra favorita do Samuel L.Jackson.

“Motherfucker” has taken on additional meanings through continued use. It has come to mean a formidable or inexorable force, as in the threat: “Payback is a bitch, but revenge is a motherfucker.” It is also an expletive expression of disgust or contempt: “Now, isn’t that a motherfucker!” “Motherfucker” also has come to be used in some circles as a general pronoun.

Jules: I want you to go in that bag, and find my wallet.
Pumpkin: Which one is it?
Jules: It’s the one that says Bad Motherfucker.