A group at a MENSA (IQ 150+) meeting were having lunch at a local restaurant when one noticed that the salt shaker was filled with pepper and the pepper shaker was filled with salt.
After a lengthy discussion they determined that they could swap the contents to match the correct shakers. All they needed was a straw and an empty saucer.
They called over their waitress (IQ much less than 150) and pointed out their concerns. Without hesitation she switched the lids, said "problem solved", and walked away from the now shocked and silenced Mensa table.