A Christian acquaintance sent me an email with this joke. It's pretty stupid and lame from an atheists perspective, however, it must seem brilliant to a theist. Notice the tired old clichés and stereotypes: Innocent little girl, arrogant atheist, faith trumps reality and science, etc.

An Atheist and a Little Girl on a Plane

An atheist was seated next to a little girl on an airplane and he turned to her and said, "Do you want to talk? Flights go quicker if you strike up a conversation with your fellow passenger."

The little girl, who had just started to read her book, replied to the total stranger, "What would you want to talk about?"

"Oh, I don't know," said the atheist. "How about why there is no God, or no Heaven or Hell, or no life after death?" as he smiled smugly.

"OK," she said. "Those could be interesting topics but let me ask you a question first.
A horse, a cow, and a deer all eat the same stuff - grass. Yet a deer excretes little pellets, while a cow turns out a flat patty, but a horse produces clumps.
Why do you suppose that is?"

The atheist, visibly surprised by the little girl's intelligence, thinks about it and says, "Hmmm, I have no idea."

To which the little girl replies, "Do you really feel qualified to discuss why there is no God, or no Heaven or Hell, or no life after death, when you don't know shit?"

And then she went back to reading her book.

I rewrote the joke, correcting the scientific misconceptions, and sent it back to her.

A little girl was seated next to a atheist on an airplane and
she turned to him and said, "Do you want to talk?  Flights go quicker if  you strike up  a conversation with your fellow passenger."
  
The atheist, who had just started to read his book, replied to the total stranger, "What would you want to talk about?"
  
"Oh, I don't know," said the little girl. "How about God, or about Heaven and Hell, or life after death?" as she smiled naively.
  
"OK," he said.  "Those could be interesting topics but let me
ask you a question first.  A horse, a cow, and a deer all eat the same stuff - grass. Yet a  deer excretes little pellets, while a cow turns out a flat patty, but a horse  produces clumps. Why do you suppose that is? And do you suppose God poops?"
  
The little girl, visibly surprised by the atheist's question, thinks about it and says, "My science teacher would say, "obviously different animal species have evolved over time and their digestive systems function differently from each other, just as their bodies differ in many, many other ways.
As far as God pooping, Hmmm, I have no idea."
  
To  which the atheist replies, "Do you really feel qualified to discuss God if you have never seen or met him, her, or it, or Heaven and Hell if you have never been there, or life after death since you never died and came back?
And which one of the thousands of Gods should we talk about, when you can only truly have knowledge of shit that exists?"
  
And then the atheist went back to reading his book. 

I saw her a month later and asked if she liked my version, she said, "No, that's just atheist crap!"