When you're about to high five someone, and your hands are just about to hit, then the other high-fiver quickly moves their hand away leaving you with a non-returned air five... you dork.
I had just gotten a new job and turned to give Amy a high five to celebrate my coolness, and she quickly dodged my hand leaving me with a faux five. I then felt very un-cool.
by natal33t September 2, 2008