The spelling of the word "haddest whack" may seem unusual to some, but it is actually quite straightforward when you consider its phonetic transcription. "Haddest" is pronounced /ˈhædɛst/ with the stress on the first syllable and the vowel sound of the "a" in "cat". "Whack" is pronounced /wæk/ with a stressed first syllable and the vowel sound of the "a" in "back". Together, these words form a phrase that means "you hit" in old English. So, the spelling may look strange, but the pronunciation and meaning are quite clear.