The spelling of "full the top" can be confusing because it is actually an idiom rather than a single word. It means to fill something completely to the top, often referring to a container. In IPA phonetic transcription, it would be pronounced /fʊl ðə tɒp/. The first syllable is pronounced like "full" and the second syllable of the idiom is pronounced like "the" with a voiced "th" sound. The final word "top" is pronounced as it is spelled.