The Legend of Rockabye Point (1955)

In the Antarctic, a fishing boat passes an iceberg where we hear the lullaby "Rockabye Baby" being sung. The captain explains how, 20 years ago, a polar bear was trying to steal fish from his ship. Alas, Chilly Willy the penguin also had his eyes on the fish. A very mean bulldog was sleeping in front of the fish, and Willy made sure the polar bear kept waking it up. Every time, the bear quickly sang a verse of "Rockabye Baby" and the dog would fall asleep again. Finally, the two of them ended up stranded atop a tall iceberg, where we see that they're still going at it, with bushy gray beards now.