Reverse Gift of the Magi

So Big Princess comes home and finds out the remote to the TV in their bedroom is lost and that you can't change the channels or adjust the volume without it. She tells little princess that she'll buy a remote if little princess will pay half. The week cruises along and Big Princess starts packing up for school. "Hey, little princess, you owe me $8 for the remote."
"I never agreed to that!"
"Fine, I'll just take it to school with me. I can use it for my TV in the dorm."
"Whatever!"

We return home from our little day trip and Big Princess has already left for school. Little princess goes in her room and turns on the TV. She comes running out...
"Mom, Big Princess left it on the Spanish channel with the volume all the way up."
"Hey, that's between you two."

Later that night Big Princess calls to let me know she arrived at school safely.
"Hey mom, can you do me a favor?"
"What dear?"
"Would you look up the remote code for my TV at school?"
"Ask your sister."
"But mom, she said she'd pay for half.."
"That's between you two."