If I have a friend who has a new interest in horror films, I usually show them something like Evil Dead or Dead Alive at first. They are both films that are kind of a mix between The Exorcist and The Three Stooges. There is humor, slapstick, gore and ghouls all mashed up together into something that is genuinely fun.
Christopher Moore's books can be a good intro into horror for those that want something that isn't too oppressively gory or dark. His books such as "Practical Demon Keeping" "Blood Sucking Fiends" and "A Dirty Job" are all more like humor lit with a good dose of horror thrown in. They are by no means horror classics that are exemplary of the genre and will make you terrified sleep with the lights off. They might, however, pique your interest in the macabre if you enjoy some of the messy bits. Then you can move along into some of the more serious stuff.