Latah

Latah is a condition occurring in Southeast Asia. Otherwise sane, Latahs compulsively imitate every motion once their attention is attracted by snapping the fingers or calling sharply.

It seemed to Sir Edwin that this patient, a young man who had never set foot outside England, was suffering from an ailment known as latah – common enough in the Malay archipelago but hitherto unknown, so far as the clinical records – admittedly not very reliable – could advise, in the temperate clime of northern Europe.

Actually, there is a debate among scholars as to whether the latah condition should be regarded as a culture-related "mental disorder" or merely as an "unusual behavior response" found in some cultures.