twice, both due to disasters
first time was when the NYC area had that big blackout... I worked on the docks helping people get across the river till it got too dark out. when we got back to our office, I reasoned that traffic was absolutely insane and there was no way in hell I was walking 10 miles to get home, so I camped out in my office and slept on the floor.
and then last winter, we had a huge blizzard and all the roads got closed. I got stuck in the office because the overnight shift couldn't get in and we can't leave our office empty (per our contract with our clients, our office must be staffed 24/7). I was the only one here and it was actually a pretty busy night, but I managed to catch a few naps throughout the night.