After attending a Mensa convention, a group of members meeting at a local cafe noticed the shaker with an S on top contained pepper and the shaker with a P on top was full of salt.
How could they swap the contents of the bottles without spilling anything and using only the implements at hand? Clearly, this was a marvellous Mensa mystery!
They presented ideas, debated them, and finally came up with what they felt was a brilliant solution involving a napkin, a straw, and an empty saucer.
When the waitress came over to take their order, they decided to dazzle her with their solution.
“Ma’am,” one of them said, “we couldn’t help but notice that the pepper shaker contains salt while the salt shaker contains…”
“Oh, sorry about that!” interrupted the waitress as she quickly unscrewed the caps of each shaker and switched them.