The text is a play on the word 'scaldophobia', which is not a real phobia but is constructed to sound like one. It combines 'scald', which means to burn with hot liquid or steam, with 'phobia', meaning fear. The humor arises from the absurdity of fearing that the toilet will flush while one is showering, potentially causing a sudden change in water temperature. However, it does not exploit different meanings of the same word or similar-sounding words.
Scaldophobia : Fear the toilet will flush while showering .