Introduction: In the dark night, a black venomous snake started hunting. It spat out a message, lazily stretched out from the tree hole and slid towards the branches. The venomous snake is as big as a hoe handle and about 1.6 Meters long. It rested on a branch, then quickly lowered its body and slid down to the back of the toilet tiles under the branch. It slipped from the women's toilet to the top of the men's toilet, and got in through a hole in the tiles.