MENSA

Mensa is an organization whose members have an IQ of 140 or higher.

A few years ago, there was a Mensa convention in San Francisco, and
several members lunched at a local café. While dining, they discovered
that their saltshaker contained pepper and their peppershaker was full
of salt. How could they swap the contents of the bottles without
spilling, and using only the implements at hand? Clearly this was a
job for Mensa! The group debated and presented ideas, and finally came
up with a brilliant solution involving a napkin, a straw, and an empty
saucer.

They called the waitress over to dazzle her with their solution.
"Ma'am," they said, "we couldn't help but notice that the peppershaker
contains salt and the saltshaker—"

"Oh," the waitress interrupted. "Sorry about that." She unscrewed the
caps of both bottles and switched them.