Why does the author have Polyphemus stop the large ram odysseus hides under and talk to the sheep?What effect does this have on the reader?

They stay in their ram-carriages until morning, when Polyphemus lets the rams pass through the entrance. Odysseus' ram, the leader, goes last, and Polyphemus asks why it is not in its customary leading position. I thought Odysseus was pretty clever.