I don't feel I own any truly gonzo rpgs. So, let's go with the item most odd on my shelves. When you look at my shelves, there is mostly horror and sci-fi with a bit of fantasy intermixed for good measure. The book that does not appear to fit in with the others is Best Friends.
Best Friends is a masterpiece about "girl friends and all their petty hatreds." The players all take on roles of girl friends, choosing who they like the most and the least, working out how to back-stab each other and come out on top.The rules brilliantly lend themself to playing it all out at the table. I highly recommend it for anyone looking for a highly social, sit down game that can be played in a single session.