[Should he laugh or facehoof? He settles for an awkward mixture of both, shaking his head and chuckling at poor Homestar's distress. When he's sufficiently amused, he reaches for a wing and lightly tugs on it.]

Let's see if I can explain this at your level:

There's a witch. She turned us into horses. You're a pegasus---winged horse. Which means, unfortunately, that you can fly if you put your meager brains to it.