There are many stories that involve "stepping out on the patio" etc. when dressed (usually at night to avoid being seen).
Imagine this scenario.
It is finally nightime. You are all dressed up and step outside onto your balcony and pull the slider door closed. Just as it closes you see your slider door security bar that was propped up in the track inside, fall down against the door, locking you out on the patio. Of course, your keys are still inside.
What would you do?