When you are in Junior High, you have sex on the brain 24/7. Every dirty word, every dirty thought is a new vista. Not a word or phrase can be thought or uttered without first trying to make a sex joke out of it.
So I was watching a Ted video on Sunday and someone was talking about a new tool (snicker snicker) that Google had called ngram (http://books.google.com/ngrams). It allows the user to search for words throughout history and see the number of references in literature.
My Jr. High persona never really grew up. So I had to search on the word Penis with a capitol P (it is important). I was presented with the graph below. You can try it yourself if you doubt the authenticity.
Sort of speaks for itself. Makes me wish I lived in 1820.