There. In the crowd. A smiling face looks at you. You're pretty sure that you don't know them, but then they raise their hand and wave. A simple gesture. A little odd, since you're almost confident at this point that you don't know them. But, in the spirit of not being rude, you lift your hand and make the simple gesture back. Then, all of the sudden, their focus shifts from what you thought was them looking at you, to them actually looking at you. They then mirror the puzzling look you had moments ago, not really sure who you are. They give you an awkward soft small and a slight wave as you realize in horror that they were not actually waving at you.
Panic.
Okay, think. What can you do in this moment to recover from this social horror? Whatever is, you'd better make the decision fast because you can already feel the blood rushing to your face, and the tangible feeling of awkward weighs heavy in the air. You have a few options. You can: (a) Pretend like you were waving at someone else, leaving them to feel like the idiot; (b) Make some explanation of "oh, I thought you were waving at me, sorry!" (c) You can turn your lame wave into an even more lame dance move and bust out a performance wherever you're at; or (d) You can do the logical thing and just pretend it never happened.
You realize that nearly a second has passed and it's decision time. Obviously, you're a pretty cool person so you want to go with something a little less lame than decision (d). You continue to panic because you're put on the spot and this is a very stressful decision to make. The other person seems pretty cool, so you finally decide to go with option (b). However, you have already mostly passed one another, so you wouldn't have time to say anything, or to fake a different wave. You're not lame, so that automatically leaves option (c) out. You're forced to go with option (d). You face palm yourself on the inside and walk away, the panic and stress finally subsiding. When you reach the comfort of your own home, you quietly eat the feelings away with a spoonful of Nutella, and are finally at peace again.