He was having dinner with his parents. Someone in their family was thinking of buying a house, and his mom, who had offered to chip in to help with the down payment, was asking if he could chip in as well. He said yes, of course. Family is family, after all. But then he thought to ask: “Would I ever get the money back?”
“Well,” she said, “I could write up a guarantee, so you’d be sure get the money eventually.” It took him a moment to understand what she was really saying – that he would get his money back when his mother was dead. “Well,” he said, trying to think of something light to say, in spite of the darker turn the conversation had taken, “by then I’ll probably be rich, so I won’t need the money.”
Then he had an inspiration. “Mom, I’ll make you a deal: It could take me a really long time to get that rich. If you will do me the favor of giving me a few decades to make my fortune before you pass on, then I won’t ask for any money back.”
She laughed, and they both agreed that it was a good deal all around.