Fangirling at my age

That was a last-ditch attempt from Crowley to get Aziraphale to stay

This is the proof that they love each other

Their love wasn't just made real because they kissed

One common usage is to make local anesthetic more effective during surgery, for instance. It's used in a number of injected medications.

Bee stings contain an enzyme very similar to this medication, so sometimes, people with bee allergies have an allergic reaction to hyaluronidase.

This is called cross-reactivity, where your body mistakes something for the thing it's actually allergic to, and has an allergic reaction anyway. For instance, sometimes people with latex allergies also are allergic to bananas and other fruits. They don't actually contain latex, but there are some similar proteins.

Apparently, hyraluronidase used in humans is derived from one of four sources: sheep testicles, cow testicles, cow testicles again, and GMO hamster ovaries.