The tradition of The Airplane began a few years ago, in my group at work (Engine Performance).
Keith's wife had a baby, and they were either given or bought a toy rocker that was all wood and looked like an old biplane. The propeller even spins.
When Amie got pregnant, Keith handed off the plane to her.
When Tim's wife got pregnant, he got the plane from Amie.
Now Amie is pregnant again, so I think Tim will hand it off again. :)
I'll just be a little bit frightened if the plane ends up on my desk one day without warning, because if they know something I don't, that would be a little scary! :)