One day an ant was out foraging when it saw a centipede. The ant had never seen a centipede before and watched it move with astonishment, two perfectly coordinated waves passed along the many legs from back to front, propelling the centipede forward.
“How do you do that? ” asked the ant
“Do what? ” said the centipede
“Move your legs – like that” said the ant
“I don’t know' said the centipede
'I never stopped to think about it”
So the centipede stopped
And thought about it
And never moved again
Stewart McKenzie
http://www.poemhunter.com/poem/joke-03-the-ant-and-the-centipede/