provar do seu próprio veneno: como dizer isso em Inglês?

So imagine yourself in this situation: You have a friend that likes to gossip about everyone, including yourself. The problem is that when he doesn't have anything to say, he makes up stories about people that end up affecting their lives in some way. One day, you and your friends think about plotting a revenge. You want him to experience the same harmful and unpleasant things he has inflicted on others. So you come up with a very bad rumor about him and very soon it starts to spread everywhere in the city.

When he wants to have it out with you guys, you tell him he needed a dose/taste of his own medicine. Again, you made him get a taste of his own medicine. Remember that medicine here doesn't apply to something good, but something more like poison. If you usually treat people badly and don't expect to receive the same treatment afterwards, someday you'll end up getting a dose of your own medicine. Take a look at a few examples:

1. Now you see how it feels to have someone call you names! You are getting a taste of your own medicine! 
2. John, who is often rude and abrupt with people, was devastated when the teacher treated him rudely. He doesn't like having a dose of his own medicine.