These hallowed forums. Such wit. Such erudition.

I am sorry for asking the following question.

When one tickles a baby's chin, it is customary to make a sound that is, approximately (ahem): "Coochy coochy coo!"

The problem: I need to use this exclamation in something I am writing.

The question: Is this the standard spelling?

Coochy coochy coo gets the most google hits so far. But is there another spelling I haven't tried that yields five, ten, twenty times more G-hits?

Tsk! Vroom! Schlump! Whaam!

If these can be confirmed with a Dictionary, why not Coochy coo?

OED citations welcome.