noun
silent fart
Colloquial term for a quiet, odorless fart; often used humorously or in casual conversation.
すかしっぺをして、誰にも気づかれなかった。
I let out a silent fart and nobody noticed.
Compound of すかし (from 透かす, 'to make transparent' or 'to do stealthily') and 屁 (へ, 'fart'), with gemination and rendaku. The exact derivation is uncertain, but it likely refers to a fart that is 'transparent' (i.e., silent and odorless).