In "Back to the Future" part II, when taking Jennifer to her (future) home, officers describe Hill valley as

"... nothing but a breeding ground for tranks, lo-bos and zipheads."

What's this futuristic slang meant to mean?

  • 10
    I would suggest that "tranks" are probably people that use tranquilisers. Commented Apr 14, 2016 at 15:42
  • Possibly names of local gangs rather than slang?
    – Kai
    Commented Apr 14, 2016 at 15:43
  • 2
    Incidentally, "ziphead" (or "zips" or "zipperheads") is Aggie slang for a senior: en.wikipedia.org/wiki/…. I think it's probably unrelated, unless there was an Aggie writer involved... Commented Apr 14, 2016 at 15:54
  • 12
    A lo-bo likely refers to someone who has had a lobotomy or removal of part of the brain.
    – Probst
    Commented Apr 14, 2016 at 15:55

2 Answers 2


As stated in the "Futurepedia" (http://backtothefuture.wikia.com/wiki/Ziphead); a Zip Head is a drug addict. The drug? "Zip".

"A ziphead was a type of person referred to by Officer Foley, possibly a person who was addicted to a drug known colloquially as "zip", or a person who, like a lo-bo, had done something to their brain."

Similarly, a lo-bo is someone who has had a brain surgery, so a cyborg of some kind- these would likely not be necessary enhancements, but "bionic implants"

"someone who has damaged their brain (through abuse of drugs or bionic implants) equivalent to a lobotomy"

It's possible that the inspiration for this word came from other sci-fi francises, such as Star Wars. See here the picture of "Lobot", or "Lo", Lando's aide in "The Empire Strikes Back":


A Trank: someone who has taken drugs via tranquilisers.

"a person under the influence of chemicals. The process of using them was to be tranked. They usually were taken via tranquilization, thus the name for those using it." [sic]

  • 2
    Well-answered... also, good first answer, and welcome to Stack Exchange :)
    – Mikasa
    Commented Apr 14, 2016 at 16:58
  • 4
    A lobotomy is a real life medical term, it didn't come from Star Wars either.
    – Probst
    Commented Apr 14, 2016 at 16:59
  • 5
    This entry cites no sources for its claim other than the movie itself, but the info on the meaning doesn't come from the movie...remember that futurepedia is a wiki that can be edited by anyone, this info is probably just (plausible) speculation by some random editor.
    – Hypnosifl
    Commented Apr 14, 2016 at 17:13
  • 3
    @Hypnosifl - Yup. All just guesswork. No sources cited whatsoever.
    – Valorum
    Commented Apr 14, 2016 at 17:29
  • 4
    The out of universe reason for this that I am sure people know is that Zemeckis and Gale were making futuristic slang vocabulary but I can find anything to support it just some magazine articles.
    – Matt
    Commented Apr 14, 2016 at 20:21

This article in Slate contains a number of solid suggestions:

The lo-bos described disdainfully by Officer Foley in the movie take this a step further: They’re “hobos,” but with the derogatory syllable “low” swapped in for extra abjection. And within the world of BTTF, lo-bo shares a resonance with low-res, a shortening of “low resolution” that figuratively conjures something shoddy or downscale. (In a computer-saturated age, poor quality images are more than technically flawed—they’re morally repugnant.) Then there’s garbed, wrong or mixed-up, redolent of both garbled and, more distantly, garbage. (Congratulations, Zemeckis, for semi-accurately predicting the ascent of garb, as in “That song is hot garb”!) Trank, of course, is a perfectly sensible shortening of tranquilizer, and an apt term for any lo-bo whose frontal lobes have been addled by sedatives.

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