What Malfoy shouts at the good guys at the end of "adult" version of Harry Potter and the Deathly Hallows.
Draco caught sight of Harry, Ron, Hermione and Ginny staring at him, nodded curtly and shouted "what yo' mudblood asses doin' starin' at me mugglefuckers!"
A person of less expertise, experience, knowledge, and understanding that causes great frustration to someone with greater knowledge, experience and expertise.
Brian is such a mugglefucker! He totally just screwed me over...I feel so mugglefucked by him!
When person with great expertise in a subject matter is screwed over, hurt, or caused great frustration by a person with lessexperience or ability in the same subject matter.