You ever know a song well and try to sing on the chorus with someone who's tweaked the holy hell out of a song for no apparent reason other than to change it?

AMEN to that! I have one acquaintence who does that to virtually every song - and she will use *her* version to accompany you when you are singing which makes it seem like YOU are off...

Now I am guilty of changing songs - not always consciously (sorry Don, Jeri, and others) though sometimes consciously (Sorry Mike) but when singing with others I try to conform to a "standard" version - or adjust to the version of whoever is leading.

I get tripped up a lot of times because sometimes even though the lyrics and melody are the same different groups do songs with very different tempos and/or interpretations.