The famous ones are
A man, a plan, a canal - Panama!
Able was I, ere I saw Elba!
Madam, I'm Adam.
Advanced students sometimes appreciate the inherent absurdity of obvious errors which don't work -
A man, a plan, a canal - Suez!
Able was I, ere I saw St Helena!
(It's OK, not everybody thinks those are funny.)
A few old favorites -
Satan, oscillate my metallic sonatas!
Sit on a potato pan, Otis!
Mr Owl ate my metal worm.
Hell, a spacecraft farce caps all, eh? (spotted that one on a blackboard at Lincoln Laboratories)
Stop! Murder us not, tonsured rumpots!
Sex, rex, nil - ever I revel in Xerxes! (on a blackboard at MIT - what the hell are they teaching there, anyway?)
And some which are more topical -
Naomi, did I moan?
Or even more to the point -
Eros? Sidney, my end is sore!
Now for the most relevant from an LPSG perspective - Maestro, a drumroll, please -
I'm, alas, a salami.