clipped from: thedailywtf.com   

Emmanuel Florac and the rest of his officemates had a bit of a problem: while they could freely leave the office as they pleased, none of them could get back in. Undoubtedly, it had something to do with the new ironclad door and accompanying electronic locking mechanism that was recently installed. Try as they might, no one’s keycard would open the door.

Throughout the day, the office manager could not get a hold of the locksmith. Call after call after call ended with a simple, “we’re sorry, this voicemail box is full; please try your call again later!”
Fortunately, Emmanuel had a better idea.
a few cardboard boxes and an unused office PC. This is what he came up with:

The following morning at 8:00AM, one of his coworkers called him up to open the door. Emmanuel put down his cup of coffee, went upstairs to his computer, and then
1) VPN to the office
2) SSH to the machine in the hall
3) Ran ~# eject /dev/scd0

And, click, the door was opened.