Nah, I got that from a friend here in town. I didn't tell it nearly as well as he did, either; though I noticed his version changed the second time I heard him tell it, too (mine was rather different from his; same punch line though).
I'm not good at remembering even regular-length jokes to retell, let alone near-shaggy-dog ones...hey! I wonder if it's time again...have y'all started any lately? I haven't been to W & F in ages.