Folklore: Simile, a saying
Its as easy as shooting monkeys in a barrel.
It means like its as easy as a piece of cake. Theres even a game out from this, where theres these monkey with claws and you try to pull them out from a bucket. I learned it when I was in elementary school. It might come from the Mid-West or Southern white It might refer to slavery. The word monkey was used to describe black people. Monkey porch implies lazy black people and is pretty derogatory.
This is a difficult metaphor to decipher, mainly because I had never heard anything remotely similar to this saying. When read closely, it is a cruel picture: having monkeys trapped in a barrel, helpless, and then shooting them is a barbaric way of asserting superiority over something. Im not sure of Chriss slavery interpretation, but it definitely signifies superiority and something about trapping an inferior group. It mocks the easiness of the action. Of course it would be easy to shoot the monkeys if they are all trapped inside a barrel.