noun
Refers to a person who acts foolishly, makes jokes, or is seen as a comical figure. Can range from light-hearted teasing to a stronger insult depending on context.
彼はクラスのこっけい者だ。
He is the class joker.
そんなことを言うなんて、君はこっけい者だな。
Saying something like that, you're a fool.
Compound of 滑稽 (こっけい, 'comical') and 者 (しゃ, 'person'). The exact historical derivation is uncertain, but the word follows a common pattern for describing a type of person.