Me and Earl and the Dying Girl by Jesse Andrews
Greg has perfected the art of blending into every social order his senior year of high school. He can hand with the jocks, the nerds, the goths, pretty much anyone. The only problem with the ability to blend with anyone, is that he has no real friends.
His mother approaches him with a request to hang with an old friend that Greg had left behind years ago. Rachel has leukemia, and needs a friend more than ever. But more and more, Greg is losing the position in school that he fought for. And he never really knows what to say to Rachel when all that races through his mind is that she is dying.
This is a hysterical book, told like the voice inside Greg's own mind.