also: むっつりすけべい
noun
quiet lecher; lecher who doesn't show it
Describes a person who is secretly lecherous or perverted but appears quiet, serious, or uninterested on the outside. Often used humorously or critically.
See also: むっつり
彼は普段は無口だけど、実はむっつりすけべらしい。
He's usually quiet, but apparently he's actually a closet lecher.
あのむっつり助平め、またエロ本を隠してるぞ。
That quiet pervert is hiding porn magazines again.
むっつり is an adverb meaning 'sullenly' or 'quietly', often describing a reserved or uncommunicative demeanor. むっつり助平 combines this with 助平 (lecher) to specifically mean a person who is lecherous beneath a quiet exterior.
助平 (すけべ) is a general term for a lecher or pervert. むっつり助平 adds the nuance of being outwardly quiet or not appearing lecherous.
Compound of むっつり (sullenly, quietly) and 助平 (lecher). The exact origin of むっつり is uncertain, but it is a mimetic word describing a reserved or uncommunicative state.