BTW, after a big long think about it, I have to concede that Shadow is right. Bucko was talking about a co-incidence, not an irony. An irony would have been:
Xtian: I love the New Testament
Bucko: I love the new Testament too
Xtian: Which verses are your favourites
Bucko: [sings some lines from a song]
It would have also been ironic if Bucko thought the Christian lad was talking about the New Testament but was in fact talking about the new Testament album.