"signal calling soldiers or sailors to quarters at night," 1680s, earlier tap-to (1640s), from Dutch taptoe, from tap "faucet of a cask" (see tap (n.1)) + toe "shut, to," from Proto-Germanic *to (see to (prep.)). "So called because police formerly visited taverns in the evening to shut off the taps of casks" [Barnhart]. In 17c. Dutch the phrase apparently was used with a transferred or figurative sense "say no more." In English, transferred sense of "drumbeat" is recorded from 1755. Hence, Devil's tattoo "action of idly drumming fingers in irritation or impatience" (1803).