A cold shower...
So... we have this fancy massage shower cabin, which has besides a normal shower also massage nozzles on the sides. And, of course, being a fancy shower cabine, it also has a fancy control panel - no plain old taps, just buttons. So, there I go, in anticipation of a nice hot shower, I set the temperature and press the 'shower' button. In that moment freezingly cold water bursts from all that nozzles.
Computers (microchips, whatever :D). Gotta love 'em :P
So, instead of cold water in your hair, you basically just jumped into Lake Superior in late December.
<font size="5">A</font>t least it wasn't scalding hot water that would cause therac-25 to repeat itself.
Have any of you seen the Dilbert Animated Series? They make fun of computerized showers too, and now I know what they're talking about.