Here's a man reading aloud the longest word in the English language. It has 189,819 letters (we can't verify that) and takes more than three hours to pronounce (or that):
The best part is that the guy has visibly grown a beard by the time he's done. Presumably this is what a Tarkovsky remake of Mary Poppins would be like.
So what's the word? Wikipedia's says that it's "Methionylthreonylthreonylglutaminylarginyl ... isoleucine" (ellipses necessary), which is the "chemical name of titin, the largest known protein." Also, there's some dispute about whether this is really a word. The next contender is only one hundredth as long so the stakes here are obviously quite high.