Used when someone slags you off for something they do themselves. It’s basically hypocrisy with a cuppa on the side. You’ll hear it when a mate gets all high and mighty, like they’ve never messed up in their life. Classic British way of saying: check yourself, because you’re not exactly spotless either.
"Dave reckons I’m tight for splitting the bill, but he’s still ‘forgetting’ his wallet like it’s a hobby. Pot calling the kettle black, mate"