I believe DnvrFox has posted previously on the history and mystique of the 50+ pie cult. Perhaps he should do so again and make it a sticky.
But basically, it's one of those "in joke" things. Being a pie lover myself I glommed onto it even without knowing the history.
If you want to get all symbolic about it, I suppose pie stands for the prevailing 50+ ethos of smelling the roses, not taking things too seriously, and so on. But that's a job for Derrida Diego*.
Anyway, with the grim news about Ford here in Motown meaning that I will have thousands more competitors for the few crappy jobs still available (my midlife change to a "hot career field" having evaporated soon after 9/11) I can really use a nice ride and a good slab of pie. With ice cream. And strong coffee. Hold the cyanide for now...
Right now it's cloudy and a bit damp but supposed to clear up in a couple of hours. So I'm waiting.
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*What I haven't seen explained yet is, what's with all this Diego stuff??