Random Events

Throughout the game, there are several random events that can occur. This is by no means an exhaustive list yet:

Farm Events

Meteorite

There is a random chance that a meteor can fall from the sky onto The Farm at night.

The Crop Fairy

During any of the growing seasons, there is a chance for the Crop Fairy to appear once you go to bed. She will select a a certain number of tiles that contain a crop you're growing, and that number may, or may not be random. Everything from a 2x4 area to a 3x5 area has been reported. This area will then immediately be available for harvesting the next day, no matter what growth level the crops were at previously.

The Witch

In a random event after you sleep, a witch will fly over your farm
Coop
If she fly over one of your Coops, she will leaving you with a Void Egg in the morning. This can occur on an empty, or full coop. Incubating the Void Egg will result in a Void Chicken.
Slime Hutch
If she fly over one of your Slime Hutches, she will turn all of the Slimes into Black/Transparent Slimes