A friend of mine bet his girlfriend he could write a sonnet in an hour — Keats is supposed to have written “On Chapman’s Homer” in an hour — and foolishly sent me the result. The first twelve lines limp along in correct enough pentameter, but he concludes with:
For even if these foes produce a battle won,
A sight so simple as her smile doth make them one.
This is about the best straight line I’ve been fed for a while; I sent him back this couplet from Pope:
A needless alexandrine ends the song,
That like a wounded snake, drags its slow length along.
(Update: Nobody, not even Seablogger, who dissects it line by line, appears to have remarked of Andrew Motion’s bit of doggerel that the second line is an alexandrine, dragging its slow length along.)