Just going on from the changed lyric thing, a folk club I was heavily involved with had a lot of Manchester City fans who loved it when "Nancy Whisky" led into a "Blue Moon" section. As far as I know it was a 'tradition' in that club only. In addition, a good friend who we see regularly substitutes "Living Doll" in the song of the same name with "Blow up Doll" followed by hissing noises. Yes, childish I know but still gets a laugh and, again, as far as I know it has been done for so long it could well be a tradition in itself! :-) (tongue in cheek but poses the question about turning a pop song into a local tradition. Maybe!)