Grandma's House

Little Johnny and his family were having a Sunday dinner at his grandmother's house.
 Everyone was seated around the table as the food was being served. When Little Johnny received his plate, he started to eat right away.
 "Johnny! Please wait until we say our prayer," said his mother.
 "I don't need to," the boy replied.
 "Of course, you do," his mother insisted. "We always say a prayer before eating at our house."
 "That's at our house." Johnny explained. "But this is Grandma's house, and she knows how to cook."