A movie is garanteed to be, "eh". One that is sure not to win any awards. One only goes to see it as a excuse to eat popcorn and other junk food with friends. Sometimes with the intention of insulting it afterword.
Also, a movie that is overly advertised in theatre previews that you get the taste memory of popcorn in your mouth when you see the commercial on t.v.
Person 1: Oh wow, Fred Clause / The Comebacks looks like such a popcorn movie. It's going to be so stupid!
Person 2: Yeah, but what else are we going to do Friday night?