The Hellions are not allowed outside for a variety of reasons. We live in a very urban area with a lot of traffic, I don't want them getting into fights or picking up parasites or diseases, and I want to protect the local wildlife; however the primary reason is that the Hellions are far too stupid to survive out there for more than five minutes. They have had brief encounters with the great outdoors, I take them outside on leashes, and once in a while they escape. Right after we moved to our current place they pried open a window. I came home and found them in the driveway.
It's worth noting that our front yard and therefore our front door are enclosed inside a chainlink fence. Instead of a backyard there is another house with another family, and the driveway runs alongside our house and back to the garage that we share. The cats had emerged from a window facing the driveway and once they descended to the ground they could not get back in. Tortie Hellion was sprawled on the driveway so I just crammed her back in through the window. Tabby Hellion was frantically running in circles, and when I went to grab him he fled in terror towards the only recognizable route back into the house: the front door.
Of course, there was a chainlink fence between him and the door, and neither of the Hellions is particularly good at solving problems. After running facefirst into the fence he backed up and tried again, then ran a few feet down the fence and did the same thing. I watched him bash his way all the way around the fence and then followed him while he bolted around the house. Once he was within sight of the front door he again ran facefirst into the fence and repeated the entire performance. While he was dashing around the house for a third try I helpfully opened the gate, allowing him to reach the front door and run indoors to safety.
Of course, the first thing he did was try to jump out the window again.