In the 70s and 80s, many TV Channels weren't broadcasting around the clock. During off time, the screen would show a colourful testcard and the speaker would croak a sweet 1000 Hz signal.
For some of us, the testcard on the screen announced bed time. Others would fumble with the remote turn in another hour or two.
Whatever the circumstances to many of us those test cards are a strange bit of childhood reminiscence.
Enter those sweet days. And this time no one will send you to bed early.