Bunny Day takes place on Easter.
Zipper T. Bunny will host this event. The eggs will be hidden underground (dig up the star cracks). If you find a foil in the eggs, then give the foil to Zipper and he will give you a piece of the
egg series.
Zipper is one of the "nicer" special visitors. You will have 30 eggs hidden in your town, 12 with foil and 18 with candy. Zipper is nice enough to NOT give you duplicate items for your 12 pieces of foil. Also, each character gets their own set of eggs.
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from the Zipper T. Bunny page:
Zipper T. Bunny shows up on
Bunny Day, which occurs once a year on Easter. Zipper has hidden a number (30) of special eggs around
town. The hidden spots are marked with a star like the fossils and gyroids, which can be dug up. The eggs contain candy or bunny foil. If bunny foil is inside an egg, you can trade this with Zipper for a random piece of the
Egg Series. Unlike
Festivale, you won't get more than one per item in the set of the series once you find all the eggs. All twelve items in the egg series can be sold to Nook for 107,776 Bells total. Click on this
link to see him in action. If you go around to the back side of Zipper, he will turn around and you can see a large zipper on his back. Each "human" player will get their own 30 eggs to find.