While eating lunch one day a girl noticed that, having shelled their hard-boiled eggs, her parents crumpled up the shells before throwing them away. She asked why they did this.
“If you don't, the witches use them for boats,” they explained. At one time this belief was quite widespread throughout Central Europe.
“Witches need boats, just like anyone else,” she replied, and threw her eggshell, uncrumpled, over her left shoulder. A whirlwind caught the shell and whisked it away.
One day the girl was fishing from an island in the middle of a river. Suddenly, due to a heavy downpour upstream, the water began to rise. Before she knew it, her boat was swept away, and soon the rapids were in danger of covering the entire island.