The pot calling the kettle black

The pot calling the kettle black is an expression that means someone says something bad about someone else, even though they do the same thing and are just as bad.

Imagine two pots sitting on a stove. One of the pots is black and the other pot is not. If the black pot said something mean about the other pot, like "You're dirty!" it would be like the black pot calling the other pot dirty, even though the black pot is just as dirty itself.

It's like when someone is called out for doing something bad and they try to make it sound like someone else is just as bad. But the other person is just like the black pot - just as guilty as them.