All children (or whoever) sit in a circle. One person walks around the circle, tapping each individual on the head and saying "duck.". Suddenly, the person taps one person and says "goose!" and then they run around the circle. The person who received the "goose" has to jump up and chase after them.

The duck-duck-gooser must run once completely around the circle and sit down in that person's spot before the person they touched catches up and tags them. If they make it, the chaser becomes the duck-duck-gooser — if they're tagged, they're still "it."

(ed: Thanks to Kevin Karpenske from the alt.fan.harry-potter newsgroup for the rules.)