When my oldest son was about six, he asked, "Daddy, were there dinosaurs when you were little?" His Dad, thinking he was talking about the plastic ones the boy was playing with, replied, "No, there weren't." My son stopped playing, looked at his father with a very serious face and said, "Boy, you really ARE old!"
I've told this story before but one time my five-year-old grand son and I were watching "Toy Story". There is a part where Buzz Lightyear, thinking he really CAN fly, jumps off a high ledge and crashes to the ground. I told my grandson that would really hurt me falling like that because I don't bounce like I used to. The five-year-old looked at me in a very comforting way and said, "That's okay Dee Dee (the name he chose to give me). You're fluffy now."