It just came up in a discussion. The test was to spot mistakes in some HTML code. I marked the "gray". The guy I did it with said that that's not a mistake. At least he thinks it's not. We were musing about that for a minute and later found out that I was wrong. Nothing major. I just felt stupid about it.
I felt especially stupid because he seemed to be rather important. While everyone's e-mail address was firstname.lastname@company.tld his was joe@company.tld.
But he was just a nice guy and apparently I did well and got my rather high salary approved.