greeting, in addition to groom, present, mount, inspect, and grasp hand, but the other greeting elements listed above are lacking. 2. See video. grimace See grin. grin Goodall: Facial expression with the corners of lips are drawn back, exposing the lower, or both upper and lower teeth. Includes van Hooffs Silent bared-teeth display. Often shown by chimpanzee threatened by another, when copulating, begging for foods, or simply watching dominant chimpanzee. May accompany male courtship. Facial expression sometimes accompanies vocalizations such as scream and squeal in copulation, and may reflect fear or frustration; but also reflect pleasure during copulation. An adult male, Fanana, occasionally shows grin and food screams during feeding on fruits such as lemon or Saba fruit or termites, which seems to express pleasure. See video. G