Well, I've been known to sing "Keep you eye upon the throttle and your hand upon the rail" more than once or twice, but that's not for "not knowing" the song, and it's true, if I had a lyric sheet handy I probably would make the same spoonerism for not bothering to glance at it. ; )

Howard, I think you summed it up pretty well 3 posts back. But I might take issue with this:
"...evidence has emerged during this discussion of singers, some of whom admit to being poor singers, who are trying to build up a large repertoire (albeit out of a book) or are aiming not to repeat a song. Now these are laudable aims, but to be setting themselves those targets when they have not mastered any of their songs is imo misguided. I believe it would be better for them as singers, and for their audience, if they were to concentrate on learning the basics, and only then to think about expanding their repertoire."
I honestly can't identify anyone who has posted in this thread who seems to fit such description.