I was running along the Hudson today and saw a colleague so I waved to him. He didn't see me, so when I was about two feet away I waved my hand a few inches from his face. He looked up, headphones pushed into his ears, and we made eye contact, but there was no recognition there. I'd said hi to him an hour earlier in the kitchen, but as a sweaty maniac waving their hands in someone's face in a public park I failed at being recognized. Once I was on the other end of this kind of interaction, but instead of my friend waving his hand in my face, he jumped across the running path at me. I always thought I'd respond to a mugging by attacking the person, but it turns out that if someone jumps out at me while I'm out jogging, all I do is shrink away and backpedal in confusion.