A weasel is an enemy of the chicken, often attacking and eating them when it is dark. If it pays a courtesy call to a chicken during New Year, it sounds strange, doesn't it? Indeed, it does this not out of kindness or politeness, but with an ulterior motive—to find an opportunity to catch the chicken and eat it up. So, never trust the apparent friendliness of a weasel. In this idiom, the weasel is a metaphor for someone with an evil intention, and the chicken is a metaphor for someone weak and vulnerable. This idiom is used to describe someone pretending to be kind and friendly, but with an evil intention at heart or having an axe to grind.

Examples
① A: Well, isn't it strange? Our boss Mr Zhang brought some watermelons to the female workers' dormitory.

B: He is just a weasel that pays a New Year call to a chicken. I wonder who is his target this time.
② A: Mr Wang is so generous, buying you such expensive gifts.

B: This is a weasel paying a New Year call to a chicken! He is afraid of me exposing his scandalous deeds.

黄鼠狼经常趁天黑偷鸡吃,是鸡的敌人。黄鼠狼在过年的时候去看望鸡,给鸡拜年,这事听起来很奇怪,是吧？对了,它并不是出于好心,而是另有目的,它要找机会把鸡吃掉,所以可千万别相信黄鼠狼的热情。在这里,黄鼠狼比喻不怀好心的人,鸡比喻弱小的人,这句话的意思就是表面上装作对别人亲热友好,实际上心里打着坏主意,另有图谋。
例句
① A：哎,今天真奇怪,张老板到女工宿舍送西瓜去了呢！ B：他呀,黄鼠狼给鸡拜年,不知道心里又在打谁的主意呢！
② A：老王够大方的啊,给你买这么贵重礼物啊！ B：这是黄鼠狼给鸡拜年嘛！他啊,是怕我把他的丑事抖搂出去。