Because we have a tiny bunny that lives under our porch. No, that's not the crazy part. The crazy kicks in when I stop in my tracks, squeal "bunny!", and point. But really, what else are you supposed to do when you see a cute itty bitty bunny rabbit?
This is the best photo I've gotten of him (her?) so far. Look very close at the center of the photo. (If you're having trouble seeing it, click here -- I have it tagged on my flickr page.)