Jacaiden - A person who has a brain the size of a marble, a head like a

A person who has a brain the size of a marble, a head like a hard-boiled egg, and a habit of being a total pain with a knot on their head.

Tweet: "My friend is a Jacaiden. He fights with the cat."

DM: "You're a Jacaiden. You're the worst."

Text: "He got sent to the principal's office. He's a Jacaiden."