The word "hobnocker" comes from the Nickelodeon show "iCarly," where it is used as a derogatory term by several characters. The showrunner of "iCarly," Dan Schneider, has admitted that the term is made up, which explains its absence from most dictionaries.
The only indication of the word's meaning within the "iCarly" universe is given when the titular character Carly asks out loud, "What is a hobnocker?" This question is followed by Carly's friend Sam whispering in Carly's ear. Carly responds, "Gross!" while Sam adds, "And illegal." Because of the vague explanation given by the show, speculation on the Internet abounds over what gross and illegal act is meant by the term.