I think it all depends on the level of maturity of the person, rather than the actual age. As for "Surfin' the Highway", yes, it is a little racy, but in a Sam and Max way. I highly doubt that any fan who has never read it before will lose all interest in the characters because of the eccentric and often inappropriate content. I've discovered the games before the reading the graphic novel and when I had a chance to read it from cover to cover, I still love the characters. In fact, it made me love them even more. If you have played the games and were able to handle the content, then I'd say you'll be able to handle "Surfin the Highway"