On a Rock

Eric (to me): "Today it's going to rain and lightening, guess we won't be hiking at your mom's house."
Amy: "I don't like lightening!"
Eric: "But it's going to lightening here as well, so we might as well be at Grandma Sherry's house."
Amy (with fear in her voice): "But is Grandma Sherry's house built on a rock?"
Eric: "Yes, it won't fall down."
Amy: (sigh of relief) "Oh! I'm glad her house is built on a rock!"