"Shannon Chan-Kent - Cupcakes [instrumental].mp3":
>(Won't you brush my mane?)
>All you gotta do is take a drop of toothpaste, add it to your brush
>If you had Pinkie's sweets then take you time, and don't be in a rush
>Brushing your teeth is such a cinch, so brush away your pain
>And when you're finished with you teeth you can even brush your mane!
>Brushing! So soft and pasty
>Brushing! Don't be too hasty
>Brushing! Brushy, brushy, brushy!

That MP3 is attached; same audio in the above-linked 6hr48min set:
https://ipfs.hypha.coop/ipfs/bafkreihlvqjpllneqfbwhovjpfyqilxrwgxgzktxc2ry6rtkdxvuu2muii
. (QmRTJ1uMbEzLrdS12ZLcWwM6b1HkqPbutfpjjcyWMmVo2b -> QmULwt2EdbyVnuYN3WUULWEzZBfEvXkZXqniownJEgd3Au -> 11th raw block)
. 12,362 bytes of padding at the end

I did an exact text search for "so brush away your pain" in !brave, !ddg, !g and also at https://desuarchive.org/_/search/text/%22so%20brush%20away%20your%20pain%22 = zero results. So those lyrics have never been posted to the Internet, or they have been but were then lost; or they have been, but to a sorta unreachable place (the deepweb or the darkweb). (!ddg=DuckDuckGo, !g=Google, !brave=Brave search.)