So almost everyone knows the Greek story of Achilles' and his heel, but for the unfamiliar he was a legendary warrior and ingenious military general who's only weakness was his heel. Of course this one vulnerability was eventually exploited and he was slain in battle.
The Romans had a habit of bootlegging Greek mythology and calling it their own, and the legend of Achilles was no exception. In the Roman version the warrior was called Bofades and it was his crotch that was his weakness and eventual downfall. Other than that the stories are virtually identical.
Romans ripping off another Greek myth isn't anything spectacular on it's own, but for some reason everyone loves hearing about Bofades nuts.