尝自己的药

《三国演义》说太医吉平有一次在头风药里暗中加了毒药端给曹操吃，曹操明知有毒，就说:“汝既读儒书，必知礼义。君有疾饮药，臣先尝之……汝为我心腹之人，何不先尝而后进?”曹操生于古代，学人说礼说义是不足奇怪的；换了是今天*******，大概就会用表示身分的英语学人说:

Please take a taste of your own¹ medicine²!
(请尝尝你自己的药吧!)

Take/get/have a taste/dose of one's own medicine是指“其人之道，其人自受”或“自尝苦果”:药当然都不会是怎么可口的。至于give somebody³ a taste/does of his own medicine，则是“以其人之道，还治其人之身”、“以牙还牙”的意思了，例如:To give him a taste of his own medicine,I did⁴ not point out to him his mistake⁵, but reported⁶ it to the boss(我实行以牙还牙，不把他的错误告诉他，却向老板报告)。