As a part of the tactics employed by the Viet Cong during the Vietnam War, the use of improvised devises to inflict injury on US and ARVN forces was key. This particular device would be buried and covered over with loose materials then placed on trails to await its victim.  An unwitting soldier would then step into the hidden bucket and become severely injured and trapped by the slightly downward pointing spikes that would prevent easy extraction of the foot.  To add to its potency, the spikes in the bucket would be dipped in human waste to inflict further injury upon the victim through exposure to infection.