The Halting Problem on Twitter:
Write H(P): true if any program P halts; false otherwise. Write C(P) that halts iff H(P) is false. C(C) halts? Contradiction. Thus, no H(P).
...or as written by Dr. Seuss:
No program can say what another will do.
Now, I won't just assert that, I'll prove it to you:
I will prove that although you might work til you drop,
you can't predict whether a program will stop.