I'd nominate Lucky Jim by Kingsley Amis, which works as both an amusing distraction and a book about honesty overcoming pretension.
Perhaps strangely, I'd also add Titus Groan, which had much the same effect on me as The Lord of the Rings had on a lot of people, and even more oddly, the essays of George Orwell. They were the first writing I read that actually seemed to be about people like me: interested in life but not part of the intellectual elite, and vaguely aware that things were unjust. Whenever I see some exceptional piece of stupidity done in the name of greed, religion or even social justice I end up thinking of "Some Thoughts on the Common Toad", where his interest in nature becomes almost mystical.