The correct spelling for the phrase "hast tantrum" is actually "has a tantrum". The word "has" is pronounced with a short "a" sound, represented in IPA transcription as /hæz/. The word "a" is pronounced with a schwa sound, represented as /ə/. The word "tantrum" is pronounced with a stressed syllable on the first syllable, represented as /ˈtæntrəm/. It's important to use the correct spelling and pronunciation to be properly understood in written and spoken communication.