- You may be looking for 21 December in the real world, celebrated as "Dalek Day" by fans.
"Dalek Day" was the name under which a Dalek making a broadcast to humanity declared that the successful invasion of Earth would now be celebrated. However, this victory was short-lived, with the Doctor soon interfering, and the Daleks retreating thereafter, although vowing to return on 1 January 2021. (AUDIO: Incoming Transmission)