spit the dummy

/S P IH1 T DH AH0 D AH0 M IY0/
verb
  1. 1

    To overreact (as an adult) to a situation, in an angry and childish manner.

    โ€œHe'll really spit the dummy when he hears that he's not going on that trip.โ€

Source: https://en.wiktionary.org/wiki/spit%20the%20dummy