Couple of things I have heard on flights when the airlines had a sense of humour:
Delta flight at ORD during the preboarding announcement:
"Ladies and Gentlemen we'd like to welcome you to our flight this morning to Atlanta. In just a few minutes we'll begin our boarding procedure with our 1st class Cabin and anyone wearing a babuche. Also if there are any passengers traveling with us from Wisconsin..please remain seated indefinitely."

On an Air Canada flight:
"Ladies and Gentlemen if everyone can be seated as quickly as possible, the pilot would like to back up from the gate, but cannot see out the rearview mirror with everyone standing."
On the same flight:
"As you all know FAA laws state that all flights are non-smoking flights. Now on Air Canada we have a very sophisticated way of handling smoking in the lavatories. If you decide to light up, our system will immediately open the bottom of the lavatory and eject you from the plane."
And finally right after landing:
"We'd like to welcome you to Toronto where the local time is... while our Captain has just made a wonderful landing, we'd like to inform you that although he has a pilot's license he certainly does not have a driver's license. So for your safety it would be best if you keep your seatbelts fastened until he has managed to find his way to the gate."