noun
A light, old-fashioned, and somewhat affectionate insult for a foolish or silly person. Often used in a teasing or playful way, similar to 'dummy' or 'nincompoop'.
そんなこともわからないの?あんぽんたん!
You don't even know that? You dummy!
あのあんぽんたんがまた
That fool messed up again.