This is a bit of cheat as I actually learned this yesterday, but today was a pretty foggy day. VSauce did a great video explaining what cousins actually are and how the relationships work.
Cousins have always been a tough concept for me. I know I have them, but I’ve never understood the whole 1st cousin, 2nd cousin, 2nd cousin 1st removed. This video does a pretty good job of breaking it all down.