At a previous employer, when I took over the Scrum Master role from someone else, I did the first retro as sort of a light-hearted joke. Just to ease into it. Because the previous Scrum Master had been a fan of making all sorts of elaborate drawings for retrospectives (little did I know it would be one of my favorite things about being a SM), I decided to just randomly draw a bear and kind of wing a retrospective concept based on the drawing.
It actually turned out pretty useful, and I did it a few times after that. Which is why I share it now.