lights-out
noun [ U ] uk/ˌlaɪtsˈaʊt/ us/ˌlaɪtsˈaʊt/
(学校或部队的)熄灯时间
(at a school where children live or in the army) the time in the evening when the lights are switched off in the room where people sleep
No talking after lights-out! 熄灯后不许说话!