A punji stick is a piece of sharpened bamboo that is usually about one to two feet long. The bamboo is cut and then hardened through exposure to fire to remove the excess water that the bamboo previously used to survive on. Punji traps usually have a form of poison or animal excrement to also create an infectious threat to anyone who is unlucky enough to fall into one. The Vietnamese typically used children and women to fashion these sticks because of how easy it is to make.
Viet Cong Tactics
Punji sticks were often grouped together and put in a dug out hole where they would be places facing upward and then covered by breakaway grass and leaves. The idea was that the soldiers would pass through the area and step on the breakaway leaves and then fall into the hole and become impaled to the point of death or immobilization. The Viet Cong considered the need for the enemy to have helicopters come to aid the wounded was a far better damage to the enemies cause than death, however some traps would be big enough to allow for upper body impalement. There were no set rules on the etiquette of the traps.