If This Book Exists, You're in the Wrong Universe is the last (latest?) book in the John Dies at the End universe by Jason Pargin (earlier titles published under the pseudonym David Wong). I've enjoyed all four books and hope that there will be more. The books are all weird and funny and somewhat philosophical but more in the stoner philosophy than the heavier and more important stuff. If you make it through the first few chapters of any of these books and find them engaging then you'll probably like the whole series.

Since I haven't talked about previous books as I read them this comment is covering the whole series but the books are so much alike in both themes and style that my feelings apply to them all.

The books are primarily from the point of view of David Wong, a bit of a loser who through chance and being friends with questionable characters finds himself wrapped up with the town's oddly prevalent supernatural side. Over the course of the four books, we follow David and his friends as they ineptly battle with cosmic forces that exist outside our universe and on a scale inconceivable to our meat brains. Some of the themes are genuinely scary and can trigger a bit of existential dread while other bits tend so far into absurdity as to be a bit comical (but that's part of the point).

Ultimately, these books are a meta comedy horror series sort of like the book version of Cabin in the Woods. They're easy to read and fast-paced, never needing to work hard to keep your attention and draw you into the next chapter. I had a few genuine chuckles at moments and found myself rooting for and invested in the characters as we see the them mature (a little) and develop (slowly and by baby steps).

Grab the first of these and give it a shot. If you don't take it too seriously, it's a really enjoyable series.