the Ceremony of the Keys
 /ðə ˌserəməni əv ðə ˈkiːz/
  /ðə ˌserəməʊni əv ðə ˈkiːz/
- a ceremony that takes place at 10 p.m. every night at the Tower of London, when a beefeater closes the gates, exchanges secret passwords with a guard, and gives him the keys.