easy mark; sitting duck; desirable prey
Idiomatic expression literally meaning 'good duck', used for a person who is an easy target for scams, exploitation, or manipulation. Often used in contexts of fraud, seduction, or taking advantage of someone naive.
He's an easy mark for con artists.
That customer is a sitting duck, so let's push the expensive products on him.
Kana plus katakana spelling is the most common written form; this word is usually written in kana.
Kanji spelling using 鴨 (wild duck), which directly conveys the 'duck' metaphor for a gullible target.
Rare kanji spelling using 好い for いい; not commonly used.
From いい (good) + カモ (duck). The 'duck' metaphor for an easy target comes from the idea that ducks are easy to hunt. The exact origin of the phrase is uncertain, but it is a common colloquialism.