Have you ever wondered what people in, say, 1400 called their genitals? No? You're a lying scumbag.
In addition to allowing one to giggle like a thirteen year-old at "love truncheon" (1888) and "central office" (1896), it's helpful in case of time travel. Let's say that you, as a guy, somehow travel back to 1523 and someone says that they want to play with your fiddle. Maybe they're a musician, maybe they want to do something more fun than playing "Greensleeves." Or you, as a woman, find yourself in 1890 and a man approaches you saying that he longs to spend eternity in Abraham's bosom. Chances are, he's probably not an evangelist (although, given evangelists' track record, he very well could be).