The "Licking Maniac" can be considered the unofficial title of the antagonist of the urban legend "Humans Can Lick Too" - in the legend the maniac is neither named nor seen but their actions are what drives the plot and leads to the terrifying conclusion.
A young girl was left alone on several accounts as her parents worked late. They bought her a dog to keep her company.
One night she was awoken by a constant dripping sound. She got up and went to the kitchen to turn off the tap properly. As she was getting back into the bed she stuck her hand under the bed, and the dog licked it.
The dripping sound continued, so she went to the bathroom and made sure the tap was turned off there, too. She went back to her bedroom and stuck her hand under the bed, and the dog licked it again.
But the dripping continued, so she went outside and turned off all the faucets out there. She came back to bed, stuck her hand under it, and the dog licked it again.
The dripping continued.. This time she listened and located the source of the dripping — it was coming from her closet. She opened the closet door, and there was her dog hanging upside down with its neck cut, and written on the window on the inside of the cupboard was, "Humans can lick, too"