Around 2003, while I was a graduate student at Berkeley, my flatmate Patxi stuck his head in my door and said

Dave, what's a manifold?

So, I told him a bit about differentiable manifolds and their many uses. The next day, he said

I told Ushnish that I asked you what a manifold was. And Ushnish laughed, and said "I'll bet he told you, didn't he!" You know that I thought you were going to say something about cars, right?

And a day or two after that, I got this picture of Oolong the rabbit from Patxi. I put it on my door. It came down when I moved, but it has made periodic reappearances on my office doors ever since.

Completely coincidentally, during the summer of 2020 my family declared that we were getting rabbits as pets. Gracie and Izzie have been a great source of amusement since.