Complex sentence: Chuck hands Cam a ring box, and Cam opens it to reveal a pebble, a reference to the penguin mating ritual in which a male penguin finds a stone and brings it to the female penguin he wants to be with.
Split into simpler sentences: Chuck hands Cam a ring box and Cam opens it to reveal a pebble. The pebble is a reference to the penguin mating ritual in which a male penguin finds a stone and brings it to the female penguin he wants to be with.