Yep. It's called a gallon ziplock bag and a rolling pin. You should be able to crack your grains and get a fairly decent crush by using a rolling pin. Remember, you just want your grains cracked open and coarsely crushed. If the grains are too fine, you'll wind up with a stuck sparge and/or lousy efficiency.
Beer so good, it's frightening.
2014: Seven Heavens Series One: Vilon, Mystic Melomel, Skeeter Pee.