NATIONAL LAMPOON'S SENIOR TRIP is a good example of a copy line making a movie poster work:
FOUR SCORE AND SEVEN BEERS AGO...
The most difficult movie poster genre is comedy. How do you market the movie AND have the film poster appear funny on its own?
For SENIOR TRIP (about a group of high school kids unleashed on DC), the client didn't want a poster showing a group of kids standing in front of a monument. So why not lose the kids? Sometimes not showing things on a poster makes a film feel bigger.
Here we see Honest Abe sporting Ray Bans, holding a beer, and wearing an "anti-Dole" button. The Bob Dole button even received a small mention in ENTERTAINMENT WEEKLY.