AKA "The Animals went in two-by-two", has become an away-game regular chant. Which has caused further divide among the Green Army (yeah, yet another thing to argue about!).
The chant is one of a kind, as it contains no words, compiring entirely of "na's" (and the occasional "Hello" if you sing that version). Which, apart from a few other 'chants' - "Great Escape" and "Ring of Fire"- which don't have lyrics. And this is a problem for some people. "Chants must have words!" they cry, "how can people join in if there's no words?", "they get confused." But why must a 'chant' have words?
If "Ring of Fire" works, and "When Johnny..." has worked so far, why try and change it (and potentially spoil it)? At Bristol City it spread like wildfire and was kept up for a long time, just because for once it was an 'easy listening' chant. If people bemoan the lack of support at football, why bemoan those who are trying to do something about it?
Wikipedia entry for "When Johnny comes Marching Home"