The move is performed by tilting the head slightly, shimmering the hands with fingers splayed either side of the face and crying "Jazz hands!" with an enthusiastic smile. Think Jack from Will and Grace.
Also *JAZZ HANDS!!!* used as an expressive punctuation on blogs and bulletin boards.
Dancer- Are these jazz hands?
DT- (Bends the students hand backwards til it breaks) No! These are Jazz hands, and they are gold!