Secret King
Someone who likes to delude themselves into thinking they're way cooler, powerful, interesting or successful with women than they actually are. Refers to the story trope of the awkward loser/nerd actually being the mastermind behind everything unbenounced to everyone, which is clearly just a wet fantasy of the gamma writers.
Look at this guy, he can barely put two words together without me cringing into oblivion and he's standing there saying he's slept with 150 women in his lifetime. What a secret king.