John Dies at the End
David Wong Audio Book

It's a drug that promises an out-of-body experience with each hit -- users can drift across time and dimensions. But some who come back are no longer human. Suddenly a silent, otherworldly invasion is underway, and mankind needs a hero. What it gets instead is John and David, a pair of college dropouts who can barely hold down jobs. Can these two stop the oncoming horror in time to save humanity? No. No, they can't.