Take the word 'crap'.
Now, obviously, this is a very recent word, being derived from the famous Thomas Crapper, inventor of the flush toilet.
WRONG! The word is very old indeed and, in fact, has Latin roots (crappa, meaning chaff). In Old English, crappe was chaff and other rubbish trodden underfoot in a barn and eventually, in the Middle Ages, crap became a generic term for things discarded. And then it went out of use – in England. Fortunately for Hollywood, although the Brits had stopped using the word by 1600, the founders of what became the Good Ol' U.S. of A. kept it going. In fact, it became so popular over there that approximately 15% of all American writing these days is the word 'crap' or one of its derivatives.
On the Web, of course, 95% of everything your read is crap, as are most statistics, economic theories, conservative policies, and reality TV shows. Only the world's great religious texts, however, are 100% pure crap.
(The picture above is of Lauren Conrad, reality TV personality, who just announced a three-book deal with Harper. Now that makes me feel really crap.)