I've always wondered this, and it turns out that my prediction was completely wrong. AntipodesMap.com has a really cool feature, where you can type in a city and it will show you where the exact opposite side of the Earth is.

I know, as kids we were always told that we'd end up in China or something if we kept digging all the way through the planet, but it turns out that we were misled.

In fact, if you were to dig straight through the Earth, you'd end up somewhere in the Indian Ocean between Madagascar and Australia. I guess when you think about it, it makes way more sense than the old China theory. First of all, we're in the Northern Hemisphere, which means we would wind up in the Southern Hemisphere, right?

The Antipodes Map is a really good time killer, or if you're in my shoes, a waster, but it's really fun to play with.