I think it was a bit disingenuous of me to think that Harry's quite that ignorant of Shakespeare or poetry structures, but hey! I doubt they taught it at Hogwarts or the Ministry. *g*
I was just lucky to remember the only really overtly dirty sonnet that Shakespeare wrote - it's the one of the last ones (151, I think) in the entire arc. I love Elizabethan double entendres. ;D