One of the "stupid pet tricks" my doctors have me perform, again and again, is the positive Babinsky reflex that proves I am brain damaged. It sounds vaguely pejorative, but is actually also known as "plantar reflex", and is commonly used as a diagnostic to indicate neurological compromise. Babinski is the name of the famed French neurologist from whom the technique takes its name.
One of the most amusing things about being tested for a positive Babinsky is that the doctor asks you to take off your shoes and socks -- to determine the status of your brain!
Then they scrape something along the bottom of the bare foot, and watch which way your toes curl. If something is wrong, the big toe and other toes flex upward and outward. The normal reflex is for the toes to curl downward, like the clenching fist.
Some doctors use a tongue depressor or some the blunt little hammer doctors use for testing reflexes. Dr. Brin, my neurologist at the U, preferred to use a key from her key ring.
I can perform this trick on request at any time. Any number of doctors have watched and nodded wisely at the uneducated and uncouth response of my big toe. It seems like a silly thing for learned doctors to be studying on, playing with their patients feet.