Not closing the blinds on the window you can't see that looks out onto an invisible street that only exists from your perspective as some sort of abstract concept. Also your "window" isn't readily visible from a distance someone has to go stumbling around in the dark and find it by physically running into it.

In other news I'm considering developing a new app and was wondering about VC funding. It's for mapping out ladders adjacent to windows down back alleys. I think it would dovetail well with nipalert.