How does Odysseus get his crewmen past Polyphemus?

Odysseus tied the male sheep into groups of 3. He and the men then wait until dawn. At dawn, the sheep start leaving the cave to feed in the pasture. Odysseus had each of his men hide underneath a middle sheep in a group of 3, so that if Polyphemus felt the sheep with his hands, he would only feel a sheep on both sides