expression
piece of cake; a walk in the park
Very casual, playful expression meaning something is extremely easy to do. Often used when showing off a simple task.
こんなのちょちょいのちょいだよ。
This is a piece of cake.
彼は難しい問題をちょちょいのちょいと解いた。
He solved the difficult problem like it was nothing.
The exact derivation is uncertain. It is a reduplicative, sound-symbolic phrase; ちょい itself is a mimetic word for a quick, light action, and the repetition adds a playful, dismissive tone.