Near the end of "The Pied Piper Power Play" when Nimnul's lair was about to explode and Dale, Monty and Gadget, along with alot of other mice, were locked in cages. Even though Chip and Zipper could save themselves, they chose not to and decided to go down with the others. Fortunately, Monty's lucky toothpick helped pick the lock of the chains holding the captives, but still, Chip choosing to die along with his friends was really noble.
Gadget cheering Tammy up and rescuing her from Fat Cat's headquarters in "Adventures In Squirrelsitting".
Zipper hugging Chip after he chooses to risk his life and defy Cassandra's prophecy to save his friends when he runs under the elephant he thinks is going to crush him.