high sign
A hand gesture used to signal someone about something. Sometimes, it refers specifically to the "OK" gesture (when the tip of the index finger and thumb touch, forming a circle). I'll give you the high sign when it's time to come out on stage.
*the high sign
Fig. a prearranged signal for going ahead with something. (Often refers to a hand signal or some other visual signal. *Typically: get ~; give someone ~.) When I got the high sign, I pulled cautiously out into the roadway. The train's engineer got the high sign and began to move the train out of the station.