You can use your phone to find movie times, view a map to the theater, buy your tickets and even watch the trailer. But you don't really need to see the trailer again, because you've already seen the two short trailers and the extended version about a hundred times on TV. You're familiar with the best jokes, the dramatic explosions and the first 2.8 seconds of the love scene. All that's left is paying to see the dull bits that fill out the rest of the film.
Or . . .
You could choose the unknown. A whole lot of unknown.