From the Quotation of the day mailing list, 2008-11-12:
"Getting an education was a bit like a communicable sexual disease. It made you unsuitable for a lot of jobs and then you had the urge to pass it on." -- Terry Pratchett, Hogfather.
(submitted to the mailing list by thom newlin)
(no subject)
There's a similar one in one of my medical textbooks (Oxford's handbook of clinical medicine):
(Genital) Herpes is like a good education. Once you have it, you can never get rid of it again. And some people just can't help themselves: they've got to pass it along.