The narrator wakes up in the middle of the night and tells himself that he's going to go to sleep as an old man. He doesn't want to look like a "little old man" in the morning, so he pretends to be his "granddaughter" and pretends that he used to be a little old man who slept with his grandfather all the time. It's funny, he says, because it reminds him of how much he loved to sleep with his grandpa all those years ago. The narrator is all, "Gee, I wish I were your grandpa." But then he realizes that it's actually been 40 years since his grandpa died, so now's the perfect time to pretend to be your grandpa.