むっつり助すけ兵べ衛え

noun

quiet lecher; lecher with a reserved exterior

Describes a person who is secretly lecherous but outwardly quiet, reserved, or seemingly uninterested in sexual matters. Often used in a colloquial, slightly old-fashioned or humorous tone.

• あの人ひとはむっつり助すけ兵べ衛えだから、普ふ段だんはおとなしいけど実じつはスケベだよ。

  That person is a quiet lecher—he seems meek but is actually perverted.

• 彼かれはむっつり助すけ兵べ衛えで、誰だれもいないと思おもってエロ本ほんを読よんでいた。

  He's a lecher with a quiet exterior; he was reading a dirty magazine thinking no one was around.