What is a Doo-da?

When our first grandson was almost a year old we happened to be watching a movie. Surviving Christmas with Ben Affleck. It was very funny. But when the part came on where he introduces his rented Doo-da to his rented family, I said "That's it Ted! That's what the grandkids can call you! They need a Doo-da! I was already Gammy so Ted needed a name too. And that is what they have all called him all these years later. I miss you Doo-da!