The spelling of the word "lappin" can be explained using the International Phonetic Alphabet (IPA). The first syllable is pronounced /læp/, as in the word "lap". The second syllable is pronounced /ɪn/, as in the word "win". Therefore, the spelling of the word "lappin" follows the convention of using the double letter "pp" to represent the /p/ sound in the first syllable, and the letter "i" to represent the /ɪ/ sound in the second syllable. This pronunciation can also be heard in the Scottish and Irish accents.