Tonight with your 13 to 17 year old
The prompt
“What's some completely ridiculous, silly thing you let yourself do that you'd never admit to a stranger?”
What to listen for
If they share it and laugh, it means they trust you with the goofy, unguarded parts of themselves that they carefully hide from the wider world, that's real intimacy, not just silliness.
If they get shy telling you, reassure them with your own reaction that this kind of silliness is safe here, not something to be embarrassed about.
If they deflect entirely, that's fine, you can share something ridiculous about yourself first to make the space feel safer for next time.
What this tells you
This shows you how comfortable they feel being completely unguarded and playful around you specifically.