Dustin goes for something a bit different. The drawing on the vial depicts the silhouette of a huge horned animal, like a mix of many different creatures that is still humanoid. All he can tell from the abstract drawing is that the creature is very muscular, has big horns and claws. Other than that, he can't tell.
"I don't know what this will do to me" he says, and thinks about drinking the whole thing, or just trying it out and taking a small sip first.
Dustin takes a very small drink barely enough to fill the space under his tongue. It tastes awful so he just swallows it. At first there's no reaction, but then he begins to feel the potion having some effect in his body. He puts the vial down and sees how his sneakers are a bit uncomfortable, like his feet had grown a little. He seems to be slightly bigger, maybe half an inch or an inch taller. He also notices how his hair has become dark and is a few inches longer, and a barely noticable stubble grew as well.
"Wow," he said. "It feels like I just went through a quick new puberty!" he says and then looked at the vial again.