Collected privately in an empty hallway while his friends played a horror game in the other room, which he returned to after the interview. I asked them if they knew, “the scary story where a girl gets her hand licked,” or, “the hand lick dog story.”

The informant heard this story for the first time at a sleepover many years ago, around the age of 11.
“So there’s this girl, and she has a dog, right? And her dog – She g-, she goes to bed and either wakes up in the morning and her dog’s licking her hand or she goes to bed and the dog’s licking her hand. And so that’s the typical, kinda, way her day goes. And then… for some reason something… [stumbles over his words] There’s some point… in the night where, like, some – where something’s licking her hand, but then it’s not – then she figures out that it’s not the dog anymore cause the dog is, like, dead in the closet or something. And then she goes to turn on the lights and realizes that there’s, like, written in blood it says… it says, I think, ‘People can lick too,’ or something like that, or something implying that it… the point is you figure out that, that the dog is dead and somebody else has been licking her hand. And that’s all I really remember.”
This version specifies the location of the dead dog, but it is the closet instead of the usual bathroom. This version does not specify where the dog is when it licks her hand. It also is worth noting that the words on the wall read, “People can lick too,” not “Humans.” It also does not specify the dripping noise that wakes up the protagonist that appears in many versions.

An analysis of several versions of this story, as well as some folkloric history, can be read here: https://www.thoughtco.com/humans-can-lick-too-3299487. Additionally, a video portrayal of the same story can be seen here at http://urbanlegendsonline.com/humans-can-lick-too/, in which the girl actively sees her hand being licked by an intruder, and does not see her missing (presumably dead) dog.