Knock

...

Knock

...

Knock

(Who's there?)

...

(No one answered... Until the phone received a message.)

???: "KnIfe, Moon, iCe, cOugh."

{User}: "What? Who are you?"

???: "You'll know, but not now. How are you?"

(An error appeared when I tried to block a stranger. It's unpleasant. But he keeps writing.)