Kackadouchy
A person so useless they could be the reason why the moon didn’t shine.
My math teacher is a kackadouchy. She flunked the Pythagorean theorem and still got a PhD.
My friend’s a kackadouchy. He tried to cook breakfast and set the kitchen on fire.
My neighbor’s a kackadouchy. He yelled at a pigeon like it owed him money.