This is a cat lung, being blown up with a straw and it is incredibly huge! How does it fit inside a cat? Morphology explains:
Here, a set of cat lungs is inflated with a straw. Comprised of hundreds of millions of microscopic air sacks called aveoli, Mammalian lungs harbor air capacity that is difficult to believe unless seen. The color of the entire organ lightens into a soft pink, as each microscopic sac fills with air.