Hiding in some conveniently-placed bushes nearby, you keep a close eye on the strange rubbery puddles littering the street. This is less productive than you've expected, as even after several minutes of intent observation the puddles do absolutely nothing whatsoever.
Nothing, that is, until a deer unexpectedly rushes out some nearby trees, splashing through a black puddle. At first it looks like nothing interesting is happening, with the deer galloping across the street and towards another forest, but then you notice something strange about the black puddle. As its surface ripples violently from the impact of the deer's hoof, it seems to lighten, gaining more color until soon it's more of a dark brown. With this done, it becomes tranquil once more, ceasing its movements.
Intrigued by the shift in the one puddle, you continue to watch, hoping to see more. After a few minutes, you spot someone walking towards the streetlight much as you had earlier tonight, looking at the puddles quizzically. The puddles remain still as he approaches, but once he's near them, you see the one the deer had trampled through squirming about. It starts to drag itself across the ground, pulling itself along in a slug-like motion, until it's next to the man. Then, with a sudden snap of motion, it wraps itself around his ankle. He looks down with surprise, and then pulls his foot up with a look of disgust on his face, apparently thinking that he'd just stepped in it by accident. The puddle holds, and his foot flies out of both his shoe and his sock, launching him backwards. You watch incredulously as the puddle moves like lightning, traveling behind him just in time for his bare foot to lodge itself into it.
Apparently frustrated, the man gives his foot a solid yank, but doesn't meet with the resistance he'd expected. Instead, the puddle goes with him, covering his foot entirely. The sudden and unexpected motion launches the poor guy to the ground, and as he sits on the cold, hard cement, he watches with a combination of curiosity and surprise on his face as the latex wobbles about for a moment... before shifting into a cartoonish deer's hoof, a mockery of the hoof on the deer you'd seen rushing through it, with a far more simplistic and solid shape. He gives it a poke, then a pull, but the latex holds fast. He inspects his new hoof for a few seconds, tugging on it a couple more times to make sure it won't come off and pulling up his pantleg to get a closer look (the hoof covers him up to just above his ankle, with a visible seam between the latex and his flesh at the top), and then tries to hobble away before anyone else comes along and sees him. You can tell by the way his expression doesn't change that he fails to notice it, but you spot a slight wriggling under his pantleg, no doubt the latex slowly and subtly making its way up his leg while he remains unaware.
Finding yourself once again alone with the puddles, you try to decide what to do next.