Meaning of “Noukin(脳筋)”
“Noukin(脳筋)” means simple and stupid.
“Noukin(脳筋)” is an abbreviation for “Noumiso(脳みそ) Made(まで) Kinniku(筋肉)”.
This is a slang.
“Noumiso(脳みそ)” means brain.
“Made(まで)” means also.
“Kinniku(筋肉)” means muscle.
So we use “Noukin(脳筋)” when we speak evil of muscular person. It means “His brain is also muscle, so that’s why he is simple and stupid.”
Some people have a bias against some people like this.
“Muscular person is simple and stupid”
“Big boobs person is stupid”
Example Conversation
A: The macho is the team leader.
B: Wow, really?
A: He is so smart.
B: I thought he is “Noukin(脳筋)”
A: あのマッチョがチームリーダーだよ
B: え、そうなの?
A: めちゃくちゃ頭いいんだよ
B: へー、脳筋だと思ってたわ。
It means “His brain is also brain, so that’s why he is simple and stupid.”
I think you meant “His brain is also muscle” / “Even his brain is muscle” ?
I made mistake!! Thank you for telling me!!