So I came outside to see what the kids were up to and what do I see:

I asked Frances what she was doing and she said, "Talking to the bus, of course." She was very matter of fact about it too. *snicker*
And then... Marshie joined in! lol

You can see why I thought all of Marshie's "soot" was from talking into the tailpipe. Even now I can't believe she was ingenious enough to figure out how to open the engine cover. I'm still stunned!