:J. Random: /J rand'm/ /n./ [generalized from {J. Random Hacker}] Arbitrary; ordinary; any one; any old. `J. Random' is often prefixed to a noun to make a name out of it. It means roughly `some particular' or `any specific one'. "Would you let J. Random Loser marry your daughter?" The most common uses are `J. Random Hacker', `J. Random Loser', and `J. Random Nerd' ("Should J. Random Loser be allowed to {gun} down other people?"), but it can be used simply as an elaborate version of {random} in any sense.
:J. Random Hacker: /J rand'm hak'r/ /n./ [MIT] A mythical figure like the Unknown Soldier; the archetypal hacker nerd. See {random}, {Suzie COBOL}. This may originally have been inspired by `J. Fred Muggs', a show-biz chimpanzee whose name was a household word back in the early days of {TMRC}, and was probably influenced by `J. Presper Eckert' (one of the co-inventors of the electronic computer).
:jack in: /v./ To log on to a machine or connect to a network or {BBS}, esp. for purposes of entering a {virtual reality} simulation such as a {MUD} or {IRC} (leaving is "jacking out"). This term derives from {cyberpunk} SF, in which it was used for the act of plugging an electrode set into neural sockets in order to interface the brain directly to a virtual reality. It is primarily used by MUD and IRC fans and younger hackers on BBS systems.
:jaggies: /jag'eez/ /n./ The `stairstep' effect observable when an edge (esp. a linear edge of very shallow or steep slope) is rendered on a pixel device (as opposed to a vector display).
:JCL: /J-C-L/ /n./ 1. IBM's supremely {rude} Job Control Language. JCL is the script language used to control the execution of programs in IBM's batch systems. JCL has a very {fascist} syntax, and some versions will, for example, {barf} if two spaces appear where it expects one. Most programmers confronted with JCL simply copy a working file (or card deck), changing the file names. Someone who actually understands and generates unique JCL is regarded with the mixed respect one gives to someone who memorizes the phone book. It is reported that hackers at IBM itself sometimes sing "Who's the breeder of the crud that mangles you and me? I-B-M, J-C-L, M-o-u-s-e" to the tune of the "Mickey Mouse Club" theme to express their opinion of the beast. 2. A comparative for any very {rude} software that a hacker is expected to use. "That's as bad as JCL." As with {COBOL}, JCL is often used as an archetype of ugliness even by those who haven't experienced it. See also {IBM}, {fear and loathing}.
A (poorly documented, naturally) shell simulating JCL syntax is available at the Retrocomputing Museum http://www.ccil.org/retro.
:JEDR: // /n./ Synonymous with {IYFEG}. At one time, people in the Usenet newsgroup rec.humor.funny tended to use `JEDR' instead of {IYFEG} or `<ethnic>'; this stemmed from a public attempt to suppress the group once made by a loser with initials JEDR after he was offended by an ethnic joke posted there. (The practice was {retcon}ned by the expanding these initials as `Joke Ethnic/Denomination/Race'.) After much sound and fury JEDR faded away; this term appears to be doing likewise. JEDR's only permanent effect on the net.culture was to discredit `sensitivity' arguments for censorship so thoroughly that more recent attempts to raise them have met with immediate and near-universal rejection.
:JFCL: /jif'kl/, /jaf'kl/, /j*-fi'kl/ vt., obs. (alt. `jfcl') To cancel or annul something. "Why don't you jfcl that out?" The fastest do-nothing instruction on older models of the PDP-10 happened to be JFCL, which stands for "Jump if Flag set and then CLear the flag"; this does something useful, but is a very fast no-operation if no flag is specified. Geoff Goodfellow, one of the Steele-1983 co-authors, had JFCL on the license plate of his BMW for years. Usage: rare except among old-time PDP-10 hackers.
:jiffy: /n./ 1. The duration of one tick of the system clock on your computer (see {tick}). Often one AC cycle time (1/60 second in the U.S. and Canada, 1/50 most other places), but more recently 1/100 sec has become common. "The swapper runs every 6 jiffies" means that the virtual memory management routine is executed once for every 6 ticks of the clock, or about ten times a second. 2. Confusingly, the term is sometimes also used for a 1-millisecond {wall time} interval. Even more confusingly, physicists semi-jokingly use `jiffy' to mean the time required for light to travel one foot in a vacuum, which turns out to be close to one *nanosecond*. 3. Indeterminate time from a few seconds to forever. "I'll do it in a jiffy" means certainly not now and possibly never. This is a bit contrary to the more widespread use of the word. Oppose {nano}. See also {Real Soon Now}.
:job security: /n./ When some piece of code is written in a particularly {obscure} fashion, and no good reason (such as time or space optimization) can be discovered, it is often said that the programmer was attempting to increase his job security (i.e., by making himself indispensable for maintenance). This sour joke seldom has to be said in full; if two hackers are looking over some code together and one points at a section and says "job security", the other one may just nod.