Symbolism, Imagery, Allegory
Sammy refers to both the shoppers in the A&P and the two girls with Queenie as followers, or "sheep." Sheep, for Sammy, symbolize people who just follow the flock, unthinkingly doing what everybody else does. Sheep are symbols of the ultimate, most blind conformity. But it's really boring when everybody acts and dresses the same way – Sammy craves difference.