Twice this week it's happened. Get dressed, lock door, step outside, close door.
Check door to see it's properly locked.
Pat yourself down to ensure you have your keys.
Damn.
Check door to see if you really locked it or if you can force it open with a push.
Pat yourself down again and double check for your keys.
Walk around the house, check the side door, the back door...
Locked.
Try the basement window. Open. And it takes about 5 minutes to force it open, it's a small window, only opens about 10 inches, and another 5 minutes to wriggle through it and drop to the basement floor. I get stuck on first on my genitals, then on my belt, but eventually fall through and work my way upstairs.