It's not much of a story, frankly. I fear I've built it up too much.
The Dude, because he can't resist touching M's stuff, found a pink purse that had a big rock in it. It's a lovely rock, white and sparkly and granite.
"Moooo-oom," M yells, "He has my special rock!"
"He can't hurt it," I yelled back.
"But what if he breaks it?"
"Maddy, it's a rock."
"What if he writes on it?"
"Then we'll wipe it off."
"But then he'll ruin it!"
"Maddy, it's a rock. He can't hurt it."
"But. Moooo-ooom. He's touching it and it's my special rock!"
Cory, being Cory, then tried to hit her with it. Which effectively changed the conversation.
And there is the story of Maddy and the rock.
FWIW - in the because my life is weird department, there is a filmmaker getting B-roll over my shoulder as I type. She just started muttering about getting the sound of typing as "room tone." Odd. Very, very odd.