Not-So Scary Snorklum

Over the hill stomped a huge, hungry Snorklum. “I AM THE SCARY SNORKLUM,” he roared “And I am going to have Mole sandwich for tea, with a little salt and pepper and chunky pickle.” But the Snorklum is scared of something too! Why do his knees knock, his tail twitch and his whiskers wibble in a worried sort of way?