After getting stung by a bee, you might make a note to be more careful of your surroundings in the future. Michael Smith had a much different reaction when a bee stung him in the testicles one day. As an entomologist who studies honeybees, he was inspired by the encounter to create a map of the most painful places to get stung on the human body. Knowing he would have trouble finding willing volunteers, Smith elected to be his own test subject.
According to National Geographic, Smith tested 25 different body parts, exposing each spot to three stings over the course of 38 days for his study, which was published in PeerJ in 2014. To induce the stings, he picked up honeybee specimens by the wings and held their stingers up to his skin for a full minute. He rated the pain of each sting on a scale of 1 to 10, and started and ended all tests with a "test sting" on his forearm for comparison.
The most painful places to get stung by a bee, in Smith's experience, aren't the parts you may expect. A sting in the scrotum, the incident that inspired the study, received a 7 out of 10 on the pain scale. It was rated just as painful as stingers in the palm, cheek, and armpit. More excruciating is a sting to the penis shaft (7.3), upper lip (8.7), and nostril (9). Smith reported that being stung in the nose triggered "sneezing, tears, and a copious flow of mucus." He theorized that the flood of mucus may be the body's defense mechanism against a bee attack in the wild.
Other body parts ranked at the opposite end of the pain spectrum. Stings to the upper arm, tip of the middle toe, and top of the skull all averaged a rating of 2.3 out of 10. Smith compared getting stung on the scalp to having an egg smashed on his head.
Though some may question the value of getting stung on purpose nearly 200 times in the name of science, Smith's hard work was recognized. In 2015, he received an Ig Nobel prize: an award that honors scientific achievements "that first make people laugh, then make them think."
[h/t National Geographic]