I like it:
On the first day God created the dog. God said, "Sit
all day by the door of your house and bark at anyone
who comes in or walks past. I will give you a life
span of twenty years."
The dog said, "That's too long to be barking. Give
me ten years and I'll give you back the other ten."
So God agreed.
On the second day God created the monkey. God said,
"Entertain people, do monkey tricks, make them
laugh. I'll give you a twenty-year life span."
The monkey said, "How boring. Monkey tricks for
twenty years? I don't think so. Dog gave you back
ten, so that's what I'll do too, okay?" And God
agreed.
On the third day God created the cow. God said,
"You must go to the field with the farmer all day
long and suffer under the sun, have calves and give
milk to support the farmer. I will give you a life
span of sixty years."
The cow said, "That's kind of a tough life you want
me to live for sixty years. Let me have twenty and
I'll give back the other forty." And God agreed
again.
On the fourth day God created man. God said, "Eat,
sleep, play, marry and enjoy your life. I'll give
you twenty years."
Man said, "What? Only twenty years?! Tell you
what, I'll take my twenty, and the forty the cow
gave back and the ten the monkey gave back and the
ten the dog gave back...that makes eighty, okay?"
"Okay", said God, "You've got a deal."
So that is why the first twenty years we eat,
sleep, play, and enjoy ourselves; for the next forty
years we slave in the sun to support our family; for
the next ten years we do monkey tricks to entertain
the grandchildren; and for the last ten years we sit
on the front porch and bark at everyone.
Life has now been explained to you.