[Author Melissa] Mohr writes that many swear-phrases we use today got their start in Medieval Europe, when the Bible provided the basis for swearing oaths — something people thought God asked of his followers in the Old Testament. (It’s where we got the “holy” in “holy shit,” for example).

But expletives predate even the spread of Christianity: The Romans’ mouths were incredibly dirty, and many of their taboos were ones Westerners still hold today. “Speaking with Roman plainness,” as the euphemism for cursing at the time went, mostly involved vividly describing genitals, which were considered both shameful and awe-inspiring — veretrum and verecundum — Mohr found. The ten worst words in ancient Latin centered on bodies and sex. Slight a Roman, and he might retaliate by threatening to perform irrumatio, or oral rape.