In the Animal Crossing series, when you find a snowball in winter, roll it around to make it bigger. After you make two, you'll be able to make a snowman. If the snowballs are the right size, then the snowman will come to life and give you gifts (the snowman furniture set). But if the snowballs aren't the right size, then the snowman will come to life and give you grief.
There is lots of different furniture to collect. You can roll balls once a day. Make a big body, and then roll a smaller one for the head on top of it.