The spelling of the word "most comeon" can be confusing. The correct spelling is actually "must-come-on," with the stress on the first syllable of both words. In IPA phonetic transcription, this would be /mʌst ˌkʌm ˈɑn/. This phrase is often used as a colloquial way of saying "you have to be joking" or "that's not believable." Understanding the correct spelling and pronunciation of common phrases can greatly improve one's communication skills.