Sometimes Y is a song sung by Sloppy Pop. In the song, he sings about the vowels a, e, i, o, and u, and how they're used between consonants to make words. During the chorus, he sings about how "Y" is sometimes a vowel.

Sloppy Pop-Vowel Song Y

The entire multi-angle view of the song, with vowels a, e, i, o, and u. Sloppy Pop is with the y.