In improvisational Jazz, the slashing of the throat gesture means "stop playing" or "last time through" and a tap on the head means go to the "beginning of the song" or the "head"(pretty obvious, huh). However, holding up crossed fingers means "go to the Bridge or B-section" and drawing a couple of circles straight up in the air means "keep repeating"... any similarities?

We also would call out key centers by "how many fingers up = x number of sharps key and how many fingers down = x number of flats key. Of course the key of "C" (no sharps or flats) was a big "C" shaped hand.