The best one was the one I sent to a friend who is a biologist -- the monkey said, "Ontogeny recapitulates phylogeny". I've infected my workspace with this -- someone sent me one on Monday, I sent messages to my staff, they sent messages to their friends in the dean's office, and by Wednesday or Thursday, someone had dared to sent one to a dean -- who came into her office and told her, "No more candy for you today!"
Dude -- you're supposed to tell her that via Monk-e-mail!
(frankly I'm a bit surprised it took so long to spread to the Dean.)
As SRI said, "The developers of the ARPANET are rolling in their graves."
And as RDH, a co-worker commented, "Who needs IM when you've got monk-e-mail!"