Galoomba
A round person who is a total pain in the ass and wants to make your life a living hell.
My teacher is a Galoomba. She gives us 100 homework problems and calls us lazy.
My friend's uncle is a Galoomba. He eats three pies for breakfast and yells at the TV.
My brother is a Galoomba. He thinks he's the best at everything and never lets me win.