Steve Jordan wrote in a.s.c.p:
The Bathtub Test
During a visit to the mental asylum, a visitor asked the Director how
you determine whether or not a patient should be institutionalized.
"Well," said the Director, "we fill up a bathtub, then we offer a
teaspoon, a teacup and a bucket to the patient and ask him or her to
empty the bathtub."
"Oh, I understand," said the visitor. "A normal person would use the
bucket because it's bigger than the spoon or the teacup."
"No," said the Director,
(spoiler)
(wait for it....)
"A normal person would pull the plug. Do you want a bed near the window?"