Just as you are about to take a sip, the wizard comes into the door. "NO!!" he cries "Not THAT bottle!!"
You tip the bottle up and swallow most of it. You then feel like there's an explosion in your belly, as it starts slowly expanding. The rest of your body soon does the same. As you grow your fur becomes green scales, your tail hardens and you sprout a pair of wings.
In an instant you're even bigger than the evil wizard, and quickly guess what you've turning into. You're a dragon!