Hiding my new baby sister in the closet because she was always screaming, and then acting like I didn't understand what my mom and grandma were saying when they kept asking me where she was. I kept playing with my toys.
Seriously? It was early in WW2 (probably about 1940 when I was three) and my father dug an air raid shelter in the back yard. When it rain the thing filled with water and he used to throw stones into it to show his friends how deep it was.