The one that always trips me up is when a man is a Stacey.
Growing up in the rural midwest, I had no idea Tracy could be a dude's name until I worked with one. (Great guy, btw.)
For me - men named Tracey
I had to call a customer once whose name was Courtney and it tripped me up when it turned out to be a male..
When I was younger, there was a couple of somewhat-distant relation who would show up occasionally to family events.
Their names were Kim, and Pinky. Kim was the wife and Pinky was the husband.