Members once used to communicate this way, seeking to get better? (3,3)
I believe the answer is:
tic tac
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for tic tac that I've seen before include "signing for course" , "Beverley experiences this" , "sweet!" , "How bookies communicate" , "Bookmakers' signals" .)