Who Killed Who?

Who Killed Who? is one of the early Tex Avery MGM Cartoons, created in 1943. The short is a ruthless parody of whodunit cases.

Beginning with an announcer proclaiming the cartoon as an educational example of how crime doesn't pay, it is set in an old, spooky house on the "Gruesome Gables". The elderly owner is murdered and, seconds later, a crafty detective arrives to investigate--but he finds out that the house is a haunted and wacky place, where finding and unmasking the murderer might prove very problematic.

Tropes used in Who Killed Who? include:

• Born in the Theatre: Done with a black silhouette of a "theater patron" who moves around despite the detective's order of "Nobody move!", followed by him knocking out the guy with a "That goes for you too, bub!"
• By the Lights of Their Eyes: Parodied when the eyes visible beyond a door peephole are left shut out when the peephole closes abruptly, forcing them to knock on the door to be let back in.
• Can't You Read the Sign?: "Do not open till X-Mas". Santa Claus himself (voiced by none other than Tex Avery himself) pops up to admonish the detective for ignoring it.
• Creepy Changing Painting: Of a comedic variety, of course--a painted woman in a bathsuit who has hastily covered herself by the time the detective peeks at the painting again.
• Dem Bones: A regular skeleton, and a red one (a Shout-Out to comedian "Red" Skelton). Earlier on, a skeletal cuckoo in a clock.
• Eek! A Mouse!: Happens to a ghost, who promptly blushes.
• Extended Disarming: The detective demands "the gun" to be placed on the table. A few seconds later, he ends up with a pile of various weapons reaching up to the ceiling.
• Hand Cannon: Exaggerated. The gun used to "kill" the victim is larger than the shooter.
• Haunted House
• I Don't Like the Sound of That Place: Gruesome Gables.
• Medium Awareness: The victim is reading a book called "Who Killed Who? (From the cartoon of the same name)". This is also how he learns of his impending murder.
• Obviously Evil: As a gag, when the detective pushes a button marked 'RING BELL FOR SUSPECTS', the butler, maid, and cheuffer come in- and they all look rather sinister.
• Peek-a-Boo Corpse: A closet that holds hundreds of corpses that fall out one by one, for (presumably) a very long time. Lampshaded:

Random corpse: Ah yes! Quite a lot of us, aren't there?

• Roger Rabbit Effect: Sort of - the live-action and the animated characters aren't seen together, but some clever cutting in the ending makes it look like this.
• Screams Like a Little Girl: The detective. Though first he uses a small pitch-pipe to find the correct octave.
• Show Some Leg: The detective resorts to this to catch the killer.
• Spinning Clock Hands: When the victim receives a message that he is going to die at midnight, he looks terrified at the cuckoo clock; there's still a few hours left, but then the hands suddenly spin all the way to midnight.