He says it all the time. I love it.
You help him get dressed. "Dee-do." You help him put his shoes on. "Dee-do." You find his "diss" (drum sticks) for him. "Dee-do."
That reminds me of something else he does that I think is super cute. When he's looking for something, he raises his hands, palm up. (I tried to get a picture, but he's not cooperating.) He does that every time we walk out of a store. "Wheh dah?" (where car?)
Oh, and he can say his own name now too. It sounds like "Mite"
What an awesome kid I have.