Since we've been in language geek territory in this thread (and any decent singer is forced to be a bit of a language geek, right qole?), I'll point out that the "y" in "my" has a diphthong. The way I say it, it's an "ah" followed by a short "ee" -- two vowel sounds mashed together. So, I assumed that the whole "Eh" in Mah-Eh-Mo was less to suggest another syllable and more to spell out the diphthong in "ae".

Also, the word "diphthong" is dangerously ripe for punning.