Yeah, I've done the same thing with my kids...make up stories on the fly when they were young and wanted a bedtime story. I made the mistake of telling about a fox and a bear in the woods. They wanted that story over and over again, but with different variations. I got so tired of trying to figure out new situations that I said one day: "There was a fox and a bear in the woods. The bear ate the fox. The end."

They didn't ask about the fox and the bear after that...