Gagooch
A person who is so full of themselves, they probably think they're a god. And they're probably wrong.
My principal is a gagooch. He thinks he's the best principal ever. He's not. He just thinks he is.
My brother is a gagooch. He said he could beat me in a race. He didn't. He ran into a tree.
My dog called my dad a gagooch. He just stared at him. Then he ate the dog's treat.