:YKYBHTLW: // /abbrev./ Abbreviation of `You know you've been hacking too long when…', which became established on the Usenet group alt.folklore.computers during extended discussion of the indicated entry in the Jargon File.
:YMMV: // /cav./ Abbreviation for {Your mileage may vary} common on Usenet.
:You are not expected to understand this: [Unix] /cav./ The canonical comment describing something {magic} or too complicated to bother explaining properly. From an infamous comment in the context-switching code of the V6 Unix kernel.
:You know you've been hacking too long when…: The set-up line for a genre of one-liners told by hackers about themselves. These include the following:
* not only do you check your email more often than your paper
mail, but you remember your {network address} faster than your
postal one.
* your {SO} kisses you on the neck and the first thing you
think is "Uh, oh, {priority interrupt}."
* you go to balance your checkbook and discover that you're
doing it in octal.
* your computers have a higher street value than your car.
* in your universe, `round numbers' are powers of 2, not 10.
* more than once, you have woken up recalling a dream in
some programming language.
* you realize you have never seen half of your best friends.
[An early version of this entry said "All but one of these have been reliably reported as hacker traits (some of them quite often). Even hackers may have trouble spotting the ringer." The ringer was balancing one's checkbook in octal, which I made up out of whole cloth. Although more respondents picked that one out as fiction than any of the others, I also received multiple independent reports of its actually happening, most famously to Grace Hopper while she was working with BINAC in 1949. —ESR]
:Your mileage may vary: /cav./ [from the standard disclaimer attached to EPA mileage ratings by American car manufacturers] 1. A ritual warning often found in Unix freeware distributions. Translates roughly as "Hey, I tried to write this portably, but who *knows* what'll happen on your system?" 2. More generally, a qualifier attached to advice. "I find that sending flowers works well, but your mileage may vary."
:Yow!: /yow/ /interj./ [from "Zippy the Pinhead" comix] A
favored hacker expression of humorous surprise or emphasis. "Yow!
Check out what happens when you twiddle the foo option on this
display hack!" Compare {gurfle}.
:yoyo mode: /n./ The state in which the system is said to be
when it rapidly alternates several times between being up and being
down. Interestingly (and perhaps not by coincidence), many
hardware vendors give out free yoyos at Usenix exhibits.
Sun Microsystems gave out logoized yoyos at SIGPLAN '88. Tourists
staying at one of Atlanta's most respectable hotels were
subsequently treated to the sight of 200 of the country's top
computer scientists testing yo-yo algorithms in the lobby.