The necessity of the appropriate "uh"

When G brought the doggie in from his first walk of the day, this morning, I asked if he'd done his "business". As new/returning dog owners, we spend an inordinate amount of time pondering and discussing his digestive tract and its production, shall we call it. But since we are also inordinately squeamish about discussing anything relating to that general topic I've suggested that, whenever possible, we speak of it in French. So when G announced that Nick had been successful not once but twice, I chimed in happily, "Il a fait caca deux fois!"

And then, of course, as happens any time I venture into my beloved French, I couldn't think of another bloody thing to say. My mouth was ready, my brain had stalled. But I noticed something about that anticipatory stance that I never had before: my muttered "uh" was in French. Really impossible to describe, the sound and shape of both the inside and outside of my mouth. Closer to an "ew" sound than an "uh", my mouth small and round and my tongue pressed against the back of my lower teeth. Even though my brain was currently void of French content, my mouth had the instinct intact. And somehow knew that if I ever would think of something to say, I'd be ready. Because you really can't get from a beautifully manufactured French to an American "uh", and back again.