*    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]