snake in the grass
见利忘义，背后搞鬼，暗中挑拨离间
口语·形容阴险小人
英文释义
someone who appears friendly or harmless but is actually treacherous or deceitful
例句
Don't trust that guy; he's a real snake in the grass.
典故来源
源自《伊索寓言》，蛇藏在草丛中不易被发现，比喻暗中使坏、表面友善的人。