BSG was really good with saving it's Holy Shit Quotient for the finales, but the Watchtower Four one, actually got the biggest "Holy Shit!" out of me - though in fairness, I've only watched up to the end of season three. I own the whole series now, but when I originally hit the end of season three I didn't, and I haven't been able to devote enough time to sit through all the seasons again to continue where I left off properly.

But, that episode got my reaction for the wrong reveal. I was surprised at whom the four were, yes, but I was more surprised that someone so in love with music in all it's forms [I have death metal and korean pop in my collection, to give an idea of the scope of my taste], had gone the whole episode without recognizing that the song they kept hearing was All Along the Watchtower.