Ignore AlphaTech's inaccurate post.
SoundPlayAmbientSpeechEvent(ped,speechEvent)
ped: the ped you want to play the speech event
speechEvent: the speech event, in your case use one of the following:
"TAUNT"
"TAUNT_AGGRO"
"TAUNT_BACK_DOWN"
"TAUNT_HARASS"
"FIGHTING"
"FIGHT_INITIATE"