Trailer Flick

When a movie is so bad and devoid of any substantial plot that watching the movie can be done by watching the trailer itself.
Snow White and the Huntsman is an example. Eragon is another (no offense to the book).

Also one of the most disappointing things in the world.

Friend: "Dude lets go watch this movie!"

Me: "No way bro, Sarah said it was a trailer flick! Just watch it later on youtube"

Friend: "That sucks man, the trailer was pretty good too.."