tic-tac
/ˈtɪktæk/(亦作tick-tack)
noun
mass noun
- (in the UK) a kind of manual semaphore used by racecourse bookmakers to exchange information（英国）（赛马时赌注登记经纪人之间用手表示的）秘密信号。
词源
mid 16th cent. (denoting a repeated ticking sound)： imitative; compare with TICK-TOCK. The current usage (originally slang) dates from the late 19th cent.