That's rich British informal
Used as a sarcastic expression to indicate that someone's fault is similar to yours.
You say I'm so mean? That's rich. You don't even chip in anything.
Jane criticized me for being late this morning. Neither did he. That's rich!
Don't blame it on me! You broke the vase too. That's rich.
1. That's a bit more expensive than expected.
2. That's rather unfair or untrue.
Totally ridiculous.
To be outperformed or outrun by someone, usually by a very wide margin.
You have to be quicker to finish this task or you will eat other my dust.