The door opens. A skeleton steps out. “A skeleton,” it answers.


Another skeleton steps out.

The pun is so obvious here (except for people who have never heard of comedian Red Skelton), I don't need to mention it.
In the MGM cartoon Who Killed Who? (1942), Tex Avery and uncredited writer Rich Hogan have come up with a fine send-up of murder mysteries, making fun of a pile of movie clichés, with Scott Bradley adding a solo organ score like you might hear on a radio detective story.
There are no credited animators.