Whose barter system is it anyway?

I have the perfect barter system with my children. If a preschooler quipped “crackers?” I agreed, “sure but let’s put away blocks, first, OK?”
If a child requested “Will you take me in town so I can buy baseball cards?”
I answered, “Sure after you vacuum the living room.”
If a teenager asked, “Can I have a few friends over?”
I said, “Sure, if you clean up before and after.”
It’s all a matter of supply and demand. I have what they want. They have the energy to clean up the house the way I want it cleaned.
I had the perfect system, until one returned from college for Christmas and thought he was a guest.
He and his brother watched videos into the wee hours of the morn. About noon the next day they came out yawning. “Can we get more videos when we take these back?”
I looked at the lounge chairs surrounded by dirty dishes, empty junk food wrappers and discarded blankets.
I walked down the hall to the bathroom where half a dozen sodden towels cluttered the floor, toothpaste dotted the mirror and the shower curtain had been left outside the tub.
Coming back through the kitchen, I surveyed the devastation of the holiday foods as I searched for a clean area on the counter.
“You want me to go out in this cold weather and pay out good money for what?”
“Videos, Mom.”
“Probably – after the living room, bathroom and kitchen are fit for human habitation again.”
“Aw, Mom. We’ll do it as soon as we get back.”
“I’ll go when it is done.” I went to my room to read.
About 45 minutes later, the living room was ready for a lady’s tea party. The bathroom had been sanitized and I could actually see the counter space in the kitchen again.
We went to the video store to the moans of the college man as he wished he were back in college.
Later it was, “Hey, can we borrow the car and go in town to the show?”
“What about …?”
The visiting royalty was suddenly homesick for college life, but they finished the work and left in a half hour.
The next week we decided to leave the crew of offspring by themselves while I accompanied my husband on a business trip. We planned to return the afternoon before my 40th birthday.
Our return was delayed. I called late in the afternoon to say that we could be late and suggest they clean up the house.
As soon as he heard my voice, the ‘guest’ bombarded me, “I cleaned the bathroom, picked up and vacuumed the living room, washed the floor in the kitchen and dining room and have all the clothes washed. Will you please, please, please drive me back to college tomorrow?”
Take him back to college a week early? Leave on my birthday for 14 hours of driving? I had never driven seven hours one way by myself. But hey! He HAD cleaned the whole house. Hmm, could be an interesting way to celebrate when life begins.
I said, “sure” and hung up. We left the next morning.
Wait a minute! Whose barter system is this anyway?