Part of the opening lines from Fear and Loathing in Las Vegas by Hunter S. Thompson. Here’s the complete passage:
We were somewhere around Barstow on the edge of the desert, when the drugs began to take hold. I remember saying something like “I feel a bit lightheaded; maybe you should drive….” And suddenly there was a terrible roar all around us and the sky was full of what looked like huge bats, all swooping and screeching and diving around the car, which was going about a hundred miles an hour with the top down to Las Vegas. And a voice was screaming: “Holy Jesus! What are these goddamn animals?”
From Adam Wilson’s Favorite Opening Lines in Literature. The other 29 are here.
Cubiyanqui 
I think that’s one of my favourite opening lines ever! I also love the opening line from I Capture The Castle – “I write this sitting in the kitchen sink…” – a very different book, but another favourite of mine.