What is "punji stick"

n. A basic weapon in the form a sharp spike in the ground, normally made from wood or bamboo and often covered in feces or other biohazardous material as a means to cause infections or disease.

The Punji stick or Punji stake is a type of booby trapped stake. It is a simple spike, made out of wood or bamboo, generally placed upright in the ground. Punji sticks are usually deployed in substantial numbers.