In Seriously. It is a Cannon that Shoots Snakes, you are required to clear one Skull, fire the Snake Cannon, and purchase a Bucket. The last item is the easiest because you can buy a Bucket from the Market. You can also complete this part by placing a Bucket in your homestead from your inventory.
I had a problem with clearing a Skull because I didn’t have a clearing for debris to spawn in my homestead. I had to place some items inside the Storage Shed to let a Skull spawn in the homestead. Plus, clearing a Skull spawn a Snake that you can shoot using the Snake Cannon.
Speaking of firing the Snake Cannon, people are having some issues with regards to this one. Zynga is already investigating the possible causes as to why the Varmint Cannons are not firing. Make sure you have Powder Kegs and a Snake as target before using the Snake Cannon.