While in line for tickets at the movies, I saw a stack of what looked like postcards for
The actual card is two pieces. One is clear plastic and on it are the outlines you see, in white, of the four main characters. So the picture you see here is black background so that the images show up. They won't scan otherwise.
This ephemeral advertising is fun. The idea, I believe the idea is that you or I will take one of these and put the plastic on your home or car window and generate some advertising for We're the Millers. Which here I have done, but in reverse of the intention.