Here’s a puzzle, “Dominant Fifth,” from William Wu’s archive attributed to Nootch. I love it for its simplicity.

“What’s the Dominant Fifth?” asked Dr. Dingo, as his daughter Cicely came in from school.
Cicely blushed. “Just a secret society,” she said. “I’m one of the vice-presidents.”
“And you’re meeting tonight; is that right?”
“How on earth did you know?” asked Cicely.
“You left this lying about. That’s no way to keep secrets, my girl.” He handed Cicely this paper:

Dominant Fifth

REASM NCNVE OTMLE SEHST TAOEI

“How did you manage to read it?” asked Cicely. “The code is known to only about eight of us.”
“Change it,” said Dingo. “Any fool can read that.”

Where and When is the next meeting scheduled?

While you’re chewing on that, here’s a classic puzzle:

You have twelve balls that seem to be identical, but one of them is actually slightly heavier or lighter. You also have a balance scale with pans that will hold the balls. Using only three weighings, how can you tell which ball is different and whether it is heavier or lighter?

Here’s a great answer to that puzzle from Marilyn vos Savant’s Parade column.