Four lines is correct.
A Clerihew is a humorous, "pseudo-biographical" ditty invented by Edmund Clerihew Bentley. As a young lad he came up with the idea when he was trying to avoid doing his homework. The name of the subject, usually a celebrity, appears at the end of Line One. (So you're more likely to find a Clerihew about someone whose name is easy to rhyme, like Donald Trump or Condoleeza Rice say, as opposed to David Ignatow or Zbignew Brzezenski.)
Here’s a couple, which like Law and Order plots, are ripped off today’s headlines:
Like a veggie out of the can, that Scooter “Libby”
Essentially scot-free from being all fibby,
He’s still driving a Bentley (not a Jeep)?
I guess it pays to be pals with The Veep.
Way down in the ratings, Ms Couric, Katie,
Gussied up for the news, all flirty and date-y,
Putting sober(?) CBS execs into a lather,
Consoled, at least, that she’s not Dan Rather.

