Does that make sense? No, not really.
You're missing the point that people frequently make offhand references to chronological age equating infirmity or inactivity. It's part of common everyday speech to say things like "I feel so old" or "I'm not that old!" or "Oh, come on, you're not that old" or "Stop acting like such an old woman." So for Rose to say the lyrical equivalent of "That's okay for old people but not for me" is good character writing.
But, yes, you have every right to question, "Why 105"? Is it just for the rhyme? Perhaps, but the history of songwriting provides much more cringe-worthy examples of words shoe-horned in just for a rhyme. And, besides, people often use an uneven number to make a point: It can seem more emphatic to say "if I live to be a hundred and a half..." or "if I live to be 117..." than to simply say "if I live to be a hundred..."
But if it really bothers you that the rhyming lyric has her say "some people of 105," what would be your solution? To have something else there that doesn't rhyme? To have her not refer to age at all because "105-year-olds can be full of joie de vivre"?
Okay, then, here's your assignment: Finish that quatrain with two lines that are better than "That's okay for some people / Of one hundred and five." All right, GO!
But don't forget that the beginning of that verse refers to people who live their lives in living rooms: meaning that they stay at home and go nowhere and do nothing, for their whole lives. It's possible, isn't it, that idea leads inexorably and inevitably to the idea of STILL being in that living room at a chronological age equaling something around a hundred? Well, let's see what you come up with.
The point is that so many of the examples in this thread--from using "career" as a verb to "not even figs...raisins" to "instead of just kept on" to "better than not"--are not "weak lyrics" or cheats"--they are twists on colloquialisms, versions of things people say, idiosyncratic choices that define character.
They "bother" you not because they're "weak," but because they are sharp.
Updated On: 12/30/13 at 01:03 PM