Olive learned a lesson recently.

She took our 11 y.o.shopping at a grocery store with a sushi restaurant attached.
The boy hadn't eaten so she sat him down in front of the sushi conveyor belt and said "Have a few plates while I shop and we will go home and make proper dinner."
Well by the time she got back, he had a stack of 10 plates and more than a $20 bill.
I always think Olive punishes with pranks (like I do) so I asked. "Did you make him eat a final wasabi one?"
No Olive read him the riot act and then both of them learned how to make sushi at home.
Lesson: You can't trust pre-pubescents with a sushi train any more than you can trust them with a tambourine.