Dear 100 Hour Board,
I'm sitting in the computer lab, and soemone is staring at me. This person looks like they should be familiar but no bells are going off, so I stare back. Then I realise that the staring was not at me but at something behind me, but by that time, the person realizes that I'm staring back and gets weirded out. Aside from the awkwardness, what is and encounter like that called?
A lost opportunity. You could have gone up and apologized for staring, explaining that they look familiar, but that you don't remember their name. You could have found a new friend. But instead, you stayed at your computer, and lost the chance. Pity.