I'll go first:

I was messing around with .htacc files (as the webmaster of a small but fairly important website within the organization) and I saw a line that was commented that had something about having your own "custom" error page. Just to see if it would work, I put in

http://www.homestarrunner.com/error

For some reason, I left it in there and my boss called me into his office a few weeks later and said someone had called him asking about some strange error message they had gotten.

No real way to talk yourself out of that one.

Many years ago I interviewed for a job as a Sun (SunOS-- before Solaris) administrator... I had already had several years of Sun-related hardware, OS and software engineering (drivers, utilities mostly) under my belt. However, the organization I had worked for OEM'd the equipment and custom racked everything... back to the story... so I interviewed pretty good and the guy took me for a tour of the computer room... so far so good. Finally after a bit we ended-up on the other side in that sort of casual "leaning-up against the equipment chit-chatting" sort of way and I remarked "So, where are the suns?" He got a sorta strange look on his face and said "You're leaning up against one!" Needless to say I didn't get the job :( even though I knew the innards inside and out-- was even the version I was used to at the time-- Sun-4M... but I'd never seen one with the skins on or even what sun's skins looked like.... (bummer)