"When Pigs Can Fly"

"When pigs can fly."
I've heard the saying so many times while growing up.
"I'll do this when pigs can fly..."
"I'll belive that when pigs can fly..."
A couple years ago I read a quote:
"They said a black man would become president when pigs could fly; A hundred days after Obama took office swine flu."
On an unrelated note I wrote this a couple nights ago:

"Mankind will reach the moon
When pigs can fly," they said
"So close your eyes and go to sleep
Don't lay awake in bed

No innovation, experimentation
Stay inside the box
The bar need not be raised
And the line we do not cross

Be a good girl, follow rules
Do what you're told to do
Don't tread the road untaken-
It's not expected from you

Keep in line and know your place
And keep your mouth shut tight
Don't believe in what can't be seen
You have only what's in sight

When pigs can fly" they said to me
But surely they don't know
That pigs did fly into my dreams
Years and years ago