Prepare for festive heartbreak: there are no boys of the NYPD choir, because there is no NYPD choir. Bah!
What there are, though, are these boys. They were in the Fairytale of New York video, apparently. They play merry Irish tunes and bung money to republican paramilitaries, as far as I can gather.
In the song, they were singing – in fact, still singing – this. They probably weren’t singing it much like Bing sings it, but you wouldn’t begrudge me a spot of Bing at Christmas, I’m sure. Lyrics here (singalonga Bing!).
The pissed old bloke in the drunk tank, meanwhile, was singing this:
It isn’t specified in the song, but if the pissed old man looked and sounded very much like one of the Dubliners, I wouldn’t be at all surprised. Hi di-diddly-idle-um, etc. and so on.