When you learn new words by reading and not so much by hearing them, it's easy to mispronounce them in your head. Then later, if you hear the word spoken, you might not even recognize it. It happens to everyone, or at least everyone who reads a lot when they are young. John Green sets the record straight on a long list of commonly mispronounced words. -via mental_floss
"You reap what you sew", "All intensive purposes", etc.