I'd have to say that The Pirates! In an Adventure with Scientists by Gideon Defoe is my favorite book right now. It's just so... odd. Funny, but odd. A must read for every nut job like me out there.

It's basically just about a bunch of pirates that decide to go on an adventure. They are lead by the Pirate Captain (whose motto is, "I like ham!") and accidently attack Charles Darwin's ship. And, well, lots of stuff happens and it all leads up to a fantastic ending which will leave you smiling, confused, and wanting more.

Peace!  

P.S.: There's a sequel, too. It's pretty much just as odd, funny, and all that good stuff, except that instead of a super intelligent monkey it has whale ventriloquism and shanty singing in Vegas.