Sergei Korsakoff's Ruble Coin

Origin
Sergei Segeievich Korsakoff (1854 - 1900) was a Russian neuropsychiatrist. As one of the greatest neuropsychiatrists of the 19th century Korsakoff published numerous works in neuropathology, psychiatry and forensic medicine. Korsakoff studied the effects of paranoia and alcoholism on the nervous system coming up with correlations between alcoholism and distinctive mental symptoms. After his passing the long term abuse of alcohol was coined Korsakoff's syndrome.

Effects
Flipping: Heads makes a person turn invisible and become forgotten, tails reverses effects.