What's the biggest blunder you've ever made?

I don't know if it's my biggest blunder, but it was during a meal, there were of course people I didn't know, and I was talking to a man, the conversation was good etc...

I'm a person who does a lot of irony and I do a lot of black humor, and at one point I said something pretty harsh about people who have cancer, of course it was humor but it was pretty hard humor, and the guy I was talking to and to whom I told the joke about cancer, had cancer himself.

I didn't know , but in the end we kept talking.
Whats the biggest blunder youve ever made?
What's the biggest blunder you've ever made?
Post Opinion