My selection is Still Life with Woodpecker, by Tom Robbins. I read this book for the first and only time in the late spring of 1994, when I was still just 18. I remember being quite bedazzled by Robbins' prose, sense of humour and quirky world view at the time. Having said that, I've been told that Robbins' work doesn't really stand up once you're past the age of about 22. Anyway - we'll see!
But please, pass along this link to your bookish friends and try to get them to play along. I've already had one entry, from Trevor J. Adams (see the comments area of the original post), and there are a couple others in the works, so stay tuned.