What sensitivities are you secretly offending when you use the words poppycock, bonfire, and porcelain? What political incorrectness are you courting when you describe someone or something as ethic? Who have you jostled, what breach of propriety have you committed when you use such remarkably innocent words as butterfly, gymnasium, and fizzle?
Unfortunate English uncovers older meanings of words that are out of joint with almost everyone's sense of propriety-word histories that reveal the deintensification of the disgusting, the generalization of the ribald, the mutation of the offensive, and occasionally the sensationalizing of the innocent.
So open the book and start having fun...or maybe you shouldn't, considering that fun originally meant...well, something different.