The Cranmon is your Thanksgiving dinner gone awry. Somewhere along the way, your ingredients must've gotten mixed up. When that happens, a Cranmon egg forms. Once it forms, there's no stopping it... it'll hatch rapidly.
For Thanksgiving, always pay attention to your recipe and follow it to the letter! Otherwise, you could spawn a Cranmon while cooking. This gigantic monster can grow rapidly and be fully formed by the end of your Thanksgiving weekend. When you notice you've created a Cranmon, it's best to place it outside and let it roam free before it can destroy anything near you—never identify yourself to a Cranmon. Stay far away!
The Cranmon leaves a foul, rotting cranberry trail in its wake. Even touching it can cause someone to become very ill.
The Town Hall in Ark City typically has to dispatch at least a few "Cranmon Cleanup Teams" shortly after Thanksgiving to manage the mayhem and bio-hazards...