Not the first, but I told a really funny "spoof" scary campfire story, Boy Scouts, circa 1967:

A traveller got into town late, and tried to get a room at a motel.
No motel rooms, but there was a large cottage available. The motel
manager said it rent it at half price because it was "haunted".

The traveller laughed and said he wasn't worried. In the wee hours of
the morning, he was awakened by tiny echoing voices...

"If the log shall turn, we shall drown".

Wandering through the rooms, the voices were coming from the bathroom.
Creeping up slowly, turned on the lights, and stopped the voices. He turns
off the light and heads back to bed, but soon hears it again...

"If the log shall turn, we shall drown".

This time he uses a small candle, and creeps in slowly, hering again...

"If the log shall turn, we shall drown".

Looks into the toilet bowl, spies two ants on top of a huge turd saying...

"If the log shall turn, we shall drown".

Did it up right with the scary flashlight look, the other kids never expected the punchline.

Learned that from an Uncle of mine.