Commonly misenterpreted for jazz hands, modulation hands are visually the same, except performed during a modulation in the piece of
music which is being performed/listened to. The modulation in most cases is of a semitone difference, followed usually by a change of key. Such modulations (and thus oppertunities for the use of modulation hands) are most commonly found in
music of a slightly more cheesy varietly, and gospel
music.
Dude! I was singin' some gospel
music in choir yesterday and I was just
like 'Modulation hands!' when we got to the key change...