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.
This phrase is used to describe something very modern or updated or something that no longer looks like what it's used to.
It has been a long time since I left my high school, and now I have to admit that it's certainly not your father's high school anymore.