also: カッパのへ
something very easy; a cinch; a piece of cake
Idiomatic expression literally meaning 'a kappa's fart', used to describe a task that is trivially easy. Often used in the phrase 河童の屁とも思わない (to think nothing of).
See also: 河童
This kind of work is a piece of cake.
彼は難しい試験も河童の屁とも思わないようだ。
He seems to think nothing of even difficult exams.
Similar meaning of something easy, but 河童の屁 is more vivid and informal.
Standard kanji spelling for the idiomatic expression.
Kana spelling; common in casual writing.
Katakana spelling for カッパ; sometimes used for emphasis or in informal contexts.
From the folkloric creature kappa (河童) and 屁 (fart). The phrase plays on the idea that a kappa's fart in water would be insignificant and effortless, hence something trivially easy.