I had several ideas, but then I remembered this situation a few years ago:
I was traveling by bike to work. When I cross the bridge, where my office is, it made a sudden "splash". I looked down and saw that a pigeon had crapped on my right sneaker. I was very upset because I wore new sneakers and pigeon shit is persistent and difficult to remove.
When I told this to my colleagues, someone said: if a pigeon shits you on the shoe while biking, then this brings happiness, because it happens so rarely!
And it's true! What an accurate timing it takes for that to happen.
So, I was grateful for the rest of the day for this special moment.
And so this is my "rara avis".
For more rara avis please visit Eric.