mother pecker

1) A mother pecker is a man who fucks his mother like a mother fucker. Unlike "mother fucker," which means a man who fucks his mother in any style, a mother pecker fucks her from behind in doggy style or licks her anus from behind.
2) Like "mother fucker," it also just insults someone to be blamed.

1. John: "Did you know Tom fucked his mom Pamela from behind so many time?"
Mike: "What?! He is indeed a mother pecker!"
2. "You, mother pecker!"