It's not really a Polish joke. Let me explain.
I am a big fan of Mystery Science Theater 3000, the show that shows bad movies with silhouettes of viewers making wisecracks about bad acting, writing, effects, and cinematography. The tagline is a reference to the MST3K episode in which the characters -- including "Tom Servo," a puppet of a robot made from a candy machine -- watched a movie called "Horror of Party Beach." In one scene, there were some nubile young women who were stranded in a wooded area when their car broke down. To the best of my memory, they were going to a store to find help and/or a phone, but the store was closed. One of the actresses in the shot was partially obscuring a sign in the store window that said, "LOOK! POLISH SAUSAGE, 19c a LB" so that all you could read was "LOOK POLISH."