It’s… a man playing the cello? What am I missing?
It’s one of those cartoons you have to stare at for a few seconds before you realize why it’s funny.
Nothing to be embarrassed about; it took me a while too. 
Not all image formats are recognized - don’t know whether it’s Discourse or this board in particular. ,jpg seems to work every time, but .jpg/bunchofcharacters may fail entirely. I’ve never had a problem with .png, but I have with .img .
You may also have to be looking at it on a device that’s large enough that you can see the detail.
If possible, try enlarging the image and looking at the hole in the cello.
Just look where the guy with the cello is looking.
Still… what’s the actual joke? There’s an eye of something, like maybe a cat or other small animal. Is the guy supposed to be concerned?
Maybe I’m just used to it, having a black cat that will pounce out at me from unlikely locations in the middle of the night, and whom I can only spot by his eyes or because he’s darker than the background even at midnight with no room lights.
It’s a person.
A person with a head/eye that’s like 1/3 the size of the cellist’s?
That’s what is so startling.
Are you not familiar with Addams’ work?
It’s creepy that something he obviously didn’t know about is lurking in his cello. Could be anything, but it certainly doesn’t belong there.
As a cartoonist, no. Had no idea until this thread that there was a comic that predated the TV series. I suppose it makes more sense in that context. Still, other works of his are funny without the extra context:
Addams’s cartoons were a regular feature in The New Yorker magazine starting in the 1930s. The members of “The Addams Family” weren’t given names until the TV series was in development in 1963 or '64.
We don’t know what it is. All we know is that it’s really creepy, and the cellist thinks so too.
The cello one is hilarious just by itself, IMO. Just the look on the guy’s face…
Right. As if he just discovered the … thing … in his cello. Addams did a good job of using the cello player’s eyes to indicate where the viewer should look. That’s what led me to the punchline, actually.
As opposed to…?
The most famous cartoon from the First World War, by Bruce Bairnsfather
Television? Movies?