by way of explanation...

This should clear up a few questions. You know, like when Wacky Neighbor looked at me and asked, "Do you date?"

I do so love the blockquote:

There is a skill that most of us city mice have. I call it the Urban Eye Slide. This is the ability to scope out one's surroundings quickly but without actually seeming to look at anything at all. This allows you to find the open seat on a crowded train, to move to the other side of the sidewalk well in advance of people handing out flyers or crappy free newspapers, or to sort of let your eyes skip over the spare-changing homeless guy on the corner, while pasting what you hope is a small wistful sympathetic smile on your face, and three steps past him you will have pangs of conscience about this but sometimes you are just not in the mood. There are downsides to the Urban Eye Slide as well. I have stood on El platforms right next to people I actually know and not seen them.

This is from Mimi Smartypants. I read it in The World According to Mimi Smartypants, which I couldn't really get through (sorry, Tiff), but the accuracy of this bit caught my eye.
If you're my friend and I've ever walked right damn past you, the above quote is why. Sorry.