Me: Hello! Hi!
Me: *Waves hand*
Me: *Jumps up and down waving both hands*
You: (You wave back)
Me: *Gives you a weird expression*
You: (Feels awkward)
Easy. Just keep it cool and . . ha! Just kidding. That’s awkward, there’s no one way to deal with it.
1) Pretend it never happened.
2) Give them the stink eye.
3) Pretend like there is someone behind them that YOU are waving at and make them believe that the joke was on them.
You might even want to shout something at the imaginary person some distance behind them. Be like “How’s it going, man?!” Of course, situation number 3 would work out fine if you were in a somewhat crowded area; you don’t want the person to turn around and see nothing but his shadow behind him. At that time, he will assume that you have some issue that requires immediate attention.
Some people try to prevent such an event from happening by doing the whole “Are you talking to me?” expression (the one in which you point at yourself and make a strangely surprised facial expression and make it seem like you’re saying something but instead you let out a mixture of a whisper and a mumble that sounds nothing like “Are you talking to me?”). At that time, the person doing the waving might shake their head and let you know that they are not talking to you, and everything goes back to normal.
I like the “talking to an imaginary person” idea better though.
[Thanks The Girlfriend]