In Batman Vol.7 Issue#.48, the Joker takes everyone at a church wedding hostage and kills them one-by-one. And just a few moments before Batman arrives at the scene, the Joker is seen casually singing "na na na na na! Batman!!" as a sort of welcome song for Batman.
Judging by the lyrics, this is very similar to (or dare I say, the same as) the famous title track of the 1966 Batman TV series by Neal Hefti starring Adam West.
So, is this some sort of homage to the 1966 TV series?
Or does the song "Na na na na Batman!" actually exist in the DC comic universe/multiverse?