Drive-In movies were never noted for the high quality of the movies they showed and that is reflected in the posters that accompanied the movies themselves.  After all, the drive-in wasn't designed with the intention of delivering quality entertainment - rather an opportune place for teenagers to park and drive (and we aren't talking cars here! 

This is a fairly long selection but one which will leave you either bemused, amused or bewildered.  Either way they will have done their job.

weetstraw.com - Drive-in Movie Posters