Tattoo

from Dictionary.com

tattoo \ta-TOO\, noun:
1. A rapid, rhythmic drumming or rapping.
2. A beat of a drum, or sound of a trumpet or bugle, giving notice to soldiers to go to their quarters at night.
3. A display of military exercises given as evening entertainment.

Tattoo is an alteration of earlier taptoo, from Dutch taptoe, "a tap(house)-shut," from tap, "faucet" + toe, "shut" -- meaning, essentially, that the tavern is about to shut.

Trivia: The more familiar tattoo, "an indelible mark or figure made by puncturing the skin and introducing some pigment into the punctures," derives from entirely different roots. That tattoo comes from Tahitian tatau.