A bird who knocks before delivering its message !
It knocked him cold.
She got hit by a bus. Why did Sally fall off the swing? She lost her arms when she was hit by a bus. Why did Sally not get back on the swing? She also lost her legs. Knock knock Who's there? Not Sally. What did Sally get for Christmas? I don't know, she couldn't open it.
To say hello from the other side.
The Fourth of Ghoul-ly!
Owl
Two Birds!
A re-postman. Or a re-post person if you feel triggered.
Obi-Gyn Kenobi.
By referee-mail.
Because you have to drop the bomb twice for her to get the message.
With a woodpecker