First Cid is an oglop. That's some kind of a bug, I guess. Then he gets turned into a frog after drinking a potion. As for what your friend said, Cid is definitely a frog, he looks like one and he says "Ribbit!" Finally, Hilda turns Cid back into human. However, if Cid cheats on Hilda again, he'll get turned into a hedgehog pie.