Hafshya
A hafshya is someone who thinks they're the best at everything and will tell you they're the best at everything, even if they're not.
My cousin's friend is a hafshya. She said she was the best at everything and then cried when she lost a game.
My mom's friend is a hafshya. She took the last piece of cake and said I was being greedy.
My teacher's brother is a hafshya. He took credit for my homework and then said I was lazy.