Instructables user Hextor writes:
Long story short, I was brand new in my office, they hadn’t given me and office key yet, and I was the last one in the office option 1 was wait 4 hours for a coworker to return, or find a way to lock the door. Jump a few years into the future, and I just recently found myself in the same circumstance, last one in the office with my wife’s car (and keys) so I had no office key. I was on my way in less than 5 minutes.
Check out how he used a piece of packing tape to lock the door.