Monkey is about as intelligent as an actual monkey. He doesn't understand a thing about the world around him.
Isaac and Miria accidentally become immortal by drinking what they thought was alcohol, and commit the stupidest crimes ever.
This show literally translates to idiot! This academy accepts the dumbest of students, including Akihisa Yoshii.
He can't drive, manage a raddish farm, he used a rare item as his son's hat, and despite having two sons name is Goku.
Naruto has come a long way. Now he is the leader of a village, is married and has kids. As a kid, he was a bit slow.
He missed that Professor Oak and his mom are getting it on, his own Pokedex implied his stupidity.
Kamina thinks that being a perv is what makes him a man. He literally wants to turn his brain off.
When Serena isn't saving the world with sparkles, she is the ditziest 14 year old you've ever seen.
Death Note is about the smartest kid in Japan getting a hold of a book that kills people by writing their names in it.
Saitama is the embodiment of the world oblivious. He devoted his life to heroism, he forgot to register with the hero association.