So I'm at a conference in LA, sitting in twilight rooms being taught at for hours a day. I'm seeing people I haven't seen for ages, and as I walk through endless convention center hallways, I see people I know, smile, nod (what IS his name?) and say "Hi", over & over again.
A friend and I go to a restaurant near the convention center for lunch. As I'm sitting on a bench waiting for our table, a familiar-looking man walks in, so I smile and nod "Hello", and he nods back and then it call comes to a screeching halt. He gives me a confused frown, and I turn beet red. He's not part of the conference, and he has no idea who I am. But I know him. He's Chris O'Donnell.
We ignored each other for the next hour. I think it was easier for him than for me.