Australian Term: To indulge in a sudden display of anger or frustration; to lose one’s temper. The phrase is usually used of an adult, and the implication is that the outburst is childish, like a baby spitting out its dummy in a tantrum and refusing to be pacified. (Dummy is a pacifier)
'There's no reason for me to spit the dummy,' he said. 'Why do I have to be a rude cunt out of the car when I've demonstrated what I can do inside of it?'