The tap code, sometimes called the knock code, is a way to encode messages, letter by letter, in a very simple way and transmit it using a series of tap sounds, hence its name. It has been commonly used by prisoners to communicate with each other. The method of communicating is usually by "tapping" either the metal bars, pipes or the walls inside the cell.
Famous quotes containing the words tap and/or code:
“A book is like a man—clever and dull, brave and cowardly, beautiful and ugly. For every flowering thought there will be a page like a wet and mangy mongrel, and for every looping flight a tap on the wing and a reminder that wax cannot hold the feathers firm too near the sun.”
—John Steinbeck (1902–1968)
“Hollywood keeps before its child audiences a string of glorified young heroes, everyone of whom is an unhesitating and violent Anarchist. His one answer to everything that annoys him or disparages his country or his parents or his young lady or his personal code of manly conduct is to give the offender a “sock” in the jaw.... My observation leads me to believe that it is not the virtuous people who are good at socking jaws.”
—George Bernard Shaw (1856–1950)