sideways Shift posture to sit beside another, to solicit grooming. See also solicit grooming. Also in bonobos. See video. sitting hunch See hunch and sit. slap Plooij SLA. Goodall: A hitting down gesture when the palmar surface of the hand is brought into contact with the objective. Done with one or both hands. Context includes aggression, charging display, drumming, social play, solicitation of courtship and play, etc. Bonobos slap in aggression, charging display, drumming and social play. See video. slap belly See slap self. slap branch Whiten et al. Branch slap. Slap branch with palmar surface of one hand for getting attention. Few adult males of M group do in courtship display. Customary at Bossou, Ta and Budongo. Branch slap described for Lomako bonobos may differ from chimpanzee