"When a guinea pig, particularly a baby guinea pig, gets excited, it just can't hold that feeling in. It pushes off from all four feet and hops straight up in the air, looking like a kernel of popcorn in a microwave.

Guinea pigs aren't the only animals that popcorn, as this behavior is called. Gazelles will do something similar to ward off predators, and even horses have been known to popcorn on occasion."