king in the castle

phrase originally coined by borat to express his pleasure at the supposed opulence of his hotel. in the vernacular, the phrase is generally meant to refer to a person who has attained great success in his life

Person A: Dude, I fucked Anna last night."
Person B: "Anna? She'd never fuck you. You're shitting me, right?
Person A: "Nah, dude; king in the castle."