I have to say it's been a pleasure joining this forum. Very nice welcomes from people and always great to learn things from so many knowledgeable fans. I thought I'd venture a first topic kick off.
When I was quite young listening to Norwegian Wood I always heard the "this bird had flown" line as having a poetic nuance. I thought John was using a gracious metaphor for a free and wild creature who couldn't be tied down by someone. Certainly not anyone crass enough to sleep in her bath.
Of course as I got older I had the epiphany one day that john was not being graciously poetic. "Bird" actually was the rather brusque slang for a girl. That completely changed my view of the song. "Wow" I thought. "That's even cooler."
I'd wager John wasn't using this latter meaning on Free as a Bird though.
Interesting to hear from others about examples of what they thought a song's lyrics meant when they were younger to when they became older and wiser.