This is an excellent feature on Juvenal which adds a bit more to the Penguin Classics introduction. Check out this link:

http://www.newcriterion.com/archive/21/apr03/juvenal.htm

A few gems here including the fact that there is a total vocabulary in all 16 satires of 4,790 words in of which a startling 2,130 are hapax legomena (words that appear only once in the entire extant Latin canon). Many of these are crude sexual terms (almost like slang words) which Juvenal used to exaggerate his anger and disdain for those he attacked. And they also sound so great (as so much slang nowadays does). To his Roman audience the unusual words would have added a sense of modernity and directness to the work (very different to the epic classical works of Vergil). They would also have shocked part of his audience and I think this shock value would have had great appeal to many readers: there’s a sense of subversiveness about the verses and they would have caused amusement both at the directness of what Juvenal is saying and the fact he even dared to say it in the first place.