The Bathtub Test
While visiting a friend in a mental aslym I asked the doctor how they know if someone needs to be institutionalized. He said they use the bathtub test. They fill a tub with water and then give the patient a teaspoon, a cup, and a bucket.
"Oh I get it." I said "a normal person would use the bucket!"
"No, a normal person would just pull the plug. Did you want a room by the window?"