Most amusing debates with fundies

[Narsil]

What's the most amusing religious debate that you've had with a fundamentalist christian?

I found that an argument I had with a fundie about extramarital sex was extremely funny, and worth saving for all eternity:

(Paraphrased)
She said: "Only unhappiness can come from extramarital sex."

I replied: "How so?"

She replied: "Well, think of an illegimate child, and when they find out that their parents weren't married when they were born, or worse, never even married. And their conception was merely an experiment for pleasure. How would YOU like that?"

I replied: "I'm pretty damn certain, speaking from experience, that my life isn't unhappy."

[Scottish Ninja]

That's a good one. I can't say I've had too many debates like such, and the ones I've had I can't remember...