The Front Door Key...Don't Leave Home Without It!

Ever!
You see, here in Waterloo only about 1 in 4 or 5 houses has what we would consider a standard front door knob. And even when you do see one, in many cases it is solely for decoration (you can't turn it to open the door). What do all the other houses, like our own, have? Absolutely nothing, other than a slit for the key. Which means that every time that front closes, it is locked on the outside and if you don't have your key, you are out of luck.
When you live in a foreign country, you pick up odd habits, but little habits that keep you from big problems. When I walk out that front door, even if I intend to leave it open, even if I'm only going to the mailbox at the street, I always grab the house key. An ill-directed gust of wind or maybe even an evil cat, and then that door closes. And then you're in trouble.
Or, as the Germans might say, you're Scheiss' ausser Glueck.
Actually, I'm making that up. They would never say that. But maybe they should.