The Uncommon Cold is episode 43 in season 2.
Muriel sneezes again and a green smoke appears to be a slug speaking to them. The slug apologized for giving Muriel the uncommon cold, but the slug told Courage that the slug is a prisoner. Courage and Muriel made it to the bayou and see fake stuffed snakes. The same slug appears and said that he was setting a statue from Big Bayou . But the slug was not alone, he has a family of slugs. They were making stuffed statues of Big Bayou every time when the evil snake sheds his skin a lot.
Courage sees Big Bayou coming out of his house and sheds his skin. Courage sees the window with the magic powers and escapes with the book. Courage arrives back into the prison. Courage sees the uncommon cold cure. He starts imitating as a chicken and strangely lays an egg and laughs. Muriel drinks the egg yolk and is cured. Just as Courage was about to set the slugs free, Big Bayou appears again and attacks Courage. The snake chases Courage and Courage reads another book page. It said "to make stuffed bayou snakes your obedient slaves, use deadly venom from a real bayou snake." Big Bayou sinks his teeth into the book when he tried to bite Courage and venom comes out of the snake's fangs. Big Bayou shakes the book in an attempt to remove it from his fangs and in doing so, venom hits the stuffed bayou snakes and they come to life. Courage says "Slave snakes, obey!" The slave snake obey Courage and Courage says "Go get him!" The slave snakes go after Big Bayou and attack him, causing the lot to float down the river.
Muriel calls out to Courage that she freed the slugs using her nail file. Back at the house, Eustace caught Muriel's cold after he ate the sneezed eggs. Eustace then sneezes causing a puff of green smoke to appear revealing that Big Bayou has been put in chains, most likely caused by the slave snakes. Courage then performs the cure for the Uncommon Cold for Eustace and laughs as the screen closes.
Easter EggAbout 4 minutes into the episode, when the slugs show Courage the spell that they used, revealed amidst the word "YADDA" in the text is a secret message:
"Bambi, you sweet thing. Can you read this? If you could why do you work at CN?" That is a quote of The Flinstones.