a douche bag
A person who talks trash, starts drama, never finishes anything, and still believes they're the best at everything.
My friend is a douche bag. He brags about his video game wins but loses every time.
My brother is a douche bag. He started a fight over a bag of chips and still thinks he won.
My mom says my dad is a douche bag because he forgot our anniversary and still thinks he’s the best dad ever.