Familyguytis

When something (typically a piece of media) is entertaining for the first few minutes/seconds, but then you realize that the content of those first few minutes/seconds is all that it has to offer. Named after Family Guy, who is infamous for having jokes that are funny for the first few seconds but then the rest of the joke is just that punchline extended, variably from a few minutes afterwards to sometimes even the entire episode.

My problem with a lot of horror movies is that they got Familyguytis; they have that one interesting gimmick or concept that reels you in but then they just refuse to expand upon it after it's introduced.