the oldest trick in the book idiom
一种老套但仍然有效的骗人把戏
a way of tricking someone that is still effective although it has been used a lot before
It was the oldest trick in the book - one man distracted me while another stole my wallet. 又是这套老把戏：一人分散我的注意力，一人趁机把我的钱包偷走。