
I know the answer to that, of course. I told him so, and explained why. Chickens, you see, are birds. Birds evolved from dinosaurs, which laid eggs. Before anything resembling the Gallus gallus domesticus existed, or even its wild ancestors existed, there were eggs. So the answer to that question is the egg, hands down, by tens of millions of years.
He seemed suitably impressed.
If I'd been a Creationist, though, I probably would have told him the opposite thing entirely. It's the chicken, I'd have said. Because God made the birds on the fifth day. Made 'em from scratch out of dirt and fluff, with no gestation. Just BAM! Skwawk! Chickens. Then, later, eggs.
Sigh. We can't even agree on that.