PZ4 is the Library of Congress classification for Science Fiction/Fantasy. Hence, any turbonerd that reads literature from this genre is thus called a "PZ4".
Librarian: "Oh great, here comes a PZ4."
PZ4 (Caped, with a very impatient demeanor): "Do you have 'The Shelters of Stone' by Jean M. Auel?"
Librarian: "That book was just published and hasn't been catalogued yet, but I can put your name on the waiting list with 10 other people."
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