I work in a three story building. My company occupies the entire third floor. Another company occupies the entire second floor. A multitude of companies occupy the first floor. Each company requires a badge to enter the facility. My company has a lunch room on the first floor. Today after eating lunch I used the freight elevator to return to my desk. Our security badge must be swiped to access the second or third floor. I swiped my badge on the elevator and hit the "3" button. The doors magically open and the janitor tries to enter the elevator but his cart of goodies is stuck on a door. I exit the elevator, hold open the door for him and he enters the elevator. I then let the door slam shut. I immediately noticed that we moved a small table from the area and replaced it with some other locked box full of individual mailboxes. I thought to myself "when did that arrive? I've only been gone 10 minutes." As I turn to walk toward my workstation I realized the wall is a bright lime green. Yeah, there isn't supposed to be a wall there. And the white walls are brighter than normal. That's when I realized, I exited the elevator on the second floor. The elevator is behind locked doors and my badge doesn't have the security clearance to open the doors. I felt too embarrassed to walk around and ask someone to let me back on the elevator. As I head to the stairwell (hoping to God that I have access to the stairs), the janitor returns for something. I just grinned and said "Oh thank God! I got off on the wrong floor." He chuckled at me a little bit.
This doesn't fall into my category of a calamity, but it sure was funny.