Someone fucking everything but their mother.
Ima Motherfucker.
People who treat you wrong and/or only want you for your money(i.e.: a "friend", a neighbor, a relative, a nigger)
I don't want to see that motherfucker, anymore!
The last person you want fucking your mother, or any of your female relatives for that matter.
"Dad molested me when I was a girl; he's a real serial motherfucker."
"Well your dad fucked your mum to concieve you, therefore he's a motherfucker".