A group made up exclusively of anyone who lets the number of
thumbs up/down determine whether or not they think an Urban
Dictionary word is of actual quality.
Coming from "Urban" as in "Urban
Dictionary" and "herd" as in "herd mentality."
"
Hmm, I'm not sure if I think this word is particularly funny or clever. But wait! It has 650 up votes and 37 down votes. I think I'll give it a
thumbs up!"
"
Wow, I think that word is hilarious, but it has 103 up votes and 512 down votes. I guess it isn't funny after all... I'll give it a down vote."
... These are primary examples of people in the urbanherd.