I’ve been wanting to post this for some time but had lost the reference. Although this has been e-mailed around without attribution, it turns out that it’s a story/radio play by award-winning SF author Terry Bisson. Here’s the full text on his website.

Voice One: “They’re made out of meat.”

Voice Two: “Meat?”

Voice One: “Meat. They’re made out of meat.”

Voice Two: “Meat?”

…

Voice One: “Oh, there’s a brain all right. It’s just that the brain is made out of meat! That’s what I’ve been trying to tell you.”

Voice Two: “So… what does the thinking?”

Voice One: “You’re not getting it, are you? You’re refusing to deal with what I’m telling you. The brain does the thinking. The meat.”

Voice Two: “Thinking meat! You’re asking me to believe in thinking meat!”

…

This first appeared in Omni Magazine, April 1991. I think it’s one of the funniest things ever published.