Halting Problem in Dr Seuss style! Quite nice! If you are unfamiliar with the halting problem read the thing and then google halting problem and click on the wikipedia link!
SCOOPING THE LOOP SNOOPER
A proof that the Halting Problem is undecidable
Geoffrey K. Pullum
(School of Philosophy, Psychology and Language Sciences, University of Edinburgh)
No general procedure for bug checks succeeds.
Now, I won’t just assert that, I’ll show where it leads:
I will prove that although you might work till you drop,
you cannot tell if computation will stop.
Scooping the Loop Snooper — Geoffrey K. Pullum.