There's a pretty levelling quote of Germaine Greer's: "Women have no idea how much men hate them." It's the kind of quote that not only knocks you ass-backwards but continues to unfurl in front of you, because the volume it speaks is only really matched by the layers in which it's applicable.
Even though the euphemism "four-letter word" only came into use during the first half of the twentieth century, I think the first and most controversial anachronistic example must be "slut. I found an unusual modern-day definition: a woman with the morals of a man. Surprised? Slut is not just a term used for women.