When my son was about seven we were in a store and he asked for a toy.
Being distracted and in a hurry, I said, "I don't have money for that right now."
He wanted to press it a bit, so he suggested I could write a check, I gave a vague answer about covering the check.
Being a problem solver my son suggested that I could go to the "Money Wall".
"The Money Wall?," I asked, actually curious.
He explained there is a wall where a person can just push buttons and money will come out.
What a child of seven didn't yet understand is you have to put something in to take something out.