Gosh, I'm really surprised to see these answers. I can't remember the last time I've actually shown anyone my boarding pass as I enter the aircraft. I've always treated it like going to the symphony: once I'm in the main entrance and they've checked my ticket there, I have no reason to show my ticket to anyone after that to get to my seat. After all, my boarding pass has just been checked as I enter the jetway, so I see no reason why it needs to be checked again at the other end of the jetway as I get onto the aircraft. And in all these years, no attendant has ever asked to see my boarding pass. I usually just smile at them and say hello as I walk into the plane and go to my seat.