Came to being as a concept and a word the first time my friend sat on a toilet at Reading music festival, a few years ago, and the human waste was piled up so high that his purple headed warrior got a poo-dunking.
Due to excessively high testosterone levels, a man with this syndrome will act in a gay manner when there are no females present. In other words, they are extremely horny... all the time. For example, suggestive comments or gestures, humping, wearing man thongs amongst men, winking at other men, caressing another man's body, and excessive physical contact are all symptoms of the "Man Thong Syndrome." These dudes ARE NOT GAY, they just require massive amounts of sex, ass, vagina, or anything else they can get.
A game played by a group of overly drunk sailors who strip down to their boxers and hike said boxers up their ass to look like a man thong. The proper head gear is a skateboard helmet.
They can try to deny it all they want but we have pictures of CMFG, Etrizzle and Nick playing man thong beer pong after a couple cases of beer.