The halting problem, à la Dr. Seuss

It has recently been rediscovered that Professor Geoff Pullum, late of the University of California at Santa Cruz but now of the University of Edinburgh, as well as of the terrific blog Language Log, has published a proof of the undecidability of the halting problem in the manner of Dr. Seuss. The original poem was published as ‘Scooping the loop snooper: an elementary proof of the undecidability of the halting problem’ in Mathematics Magazine 73.4, 319–320, and can be found here (JSTOR access required) or reprinted, probably not entirely legally but entirely freely, here.