The word "kustok" can be a bit tricky to spell correctly. It is pronounced [ˈkʌstɑk], with the stress on the first syllable. The first sound, "ku-", is a short "u" sound followed by a hard "k" sound. The second syllable, "-sto-", contains a short "o" sound followed by a "st" consonant cluster. The final syllable, "-k", is simply a hard "k" sound. One way to remember the spelling is to associate it with the word "custard," which has a similar sound and spelling pattern.