Imagine you have a toy that you really like playing with, but your friend takes it away from you and says you're not allowed to have it anymore. This makes you really upset and you ask your mom and dad to help you get your toy back. They say they will help you, but you have to go to a special room where some grown-ups will decide if you should get your toy back.
When you get to the special room, there are a lot of people there watching you. These people are called judges, and they are supposed to decide if you get your toy back. However, some of them don't like you and already think you did something wrong, even though you didn't do anything bad.
So, instead of really trying to help you get your toy back, these judges pretend like they are giving you a fair trial but are actually just trying to make you look bad and guilty. This kind of trial is called a show trial because it's not really about getting the truth or justice, but just about showing off to other people and making you look bad. It's not right, and it can be really unfair!