Jack Big Potato
A person who acts like they're the most important person in the room, but they're just a sad, messy potato who can't even tie their shoes.
My brother is Jack Big Potato. He thinks he's the best at everything but can't even do his homework.
My teacher called the principal Jack Big Potato because he tried to wear a suit and it looked like a potato suit.
My dog ran away from my neighbor because he was Jack Big Potato. He barked like a madman.