Attention, parents: Turns out those MPAA ratings do mean something. A new study from Dartmouth University has found that middle schoolers who are forbidden from watching R-rated films are much less likely to consume alcohol. Twenty-five percent of middle schoolers whose parents let them watch R-rated movies "all the time" had tried a little booze without the knowledge of their unsuspecting parents, the report found. Meanwhile, only 3 percent of those who were "never allowed" to watch R-movies had tried a drink. Dartmouth professor and co-author of the study James Sargent said that, above all, the content of a film trumped its rating: Parents shouldn't "let their children watch 10 PG-13 movies a week. I would argue a lot of PG-13 movies should be rated R."