Dancing using only your hands. Usually seen by people going about their business with headphones on, who are totally feeling a tune, but don't want to draw attention to themselves in public by busting a move.
Therefore, physical appreciation of the music is shown by hancing with their arms at their sides nonchalantly, and tapping their fingers on their palms/music device, and/or clench their hands in time with the music.
Dude 1: Hey man, check out that girl on the other side of the street with the headphones. That's some badass hancing fo sho.
Dude 2: Word. From her hance moves I guess she's listening to...The Cure vs Justin Timberlake mashup? Fawesome.