So apparently the magic phrase that instantly gets people to do tongues correctly is this:
“Can’t you just do it in your regular voice?”
Your regular voice is the one you use when talking to friends you’re comfortable with, ie not feeling awkward or stifled or nervous.
I don’t mean that God is just your buddy that you should feel totally comfortable around. But I do mean that you can speak to him in your regular voice without getting all dramatic about it.