I once tried to perform an internet banking task only to find out I had to call in by phone and enable it first. So I did, and I was asked a few security questions about my data, one of them was: what's the name of your spouse?

I gave the name, was asked to repeat it, so I did, they informed me I was wrong.

I still don't know if they had a name with a typo in the records, a maidem name, or maybe they didn't even have her name (don't remember telling the bank about marital status) and it was some sort of trick question where I was supposed to answer I'm single (even though I wasn't).