a device for making a tapping sound on a windowpane or door as a prank: it consists typically of a weight hung next to the window, etc. and manipulated from a distance by a string
Origin:
echoic redupl. of tick
See ticktack in American Heritage Dictionary 4
also tic-tac
noun
A steady ticking sound, as of a clock.
A prankster's device for tapping on a door or window from a distance.