A noted psychiatrist was a guest at
a blonde gathering, and his hostess
naturally broached the subject in which
the doctor was most at ease. “Would
you mind telling me, Doctor,” she asked,
“how you detect a mental deficiency in
somebody who appears completely normal?”

“Nothing is easier,” he replied. “You ask
a simple question which anyone should answer
with no trouble. If he hesitates, that puts
you on the track.”

“What sort of question?”

“Well, you might ask him, ‘Captain Cook
made three trips around the world and
died during one of them. Which one?’

The blonde thought a moment, then said
with a nervous laugh, ”You wouldn't happen
to have another example would you? I must
confess I don't know much about history."