This is a fragment of a song that Beck included in Song Reader
You can hear what it sounds like here
Beck, in putting Song Reader together, borrowed a lot of phrases and images from much much older sheet music. "Fluffy Ruffles" is one of them. Not just a goofy little fragment, the title was a fairly common one in sheet music in the early 20th century. In fact, there seems to be numerous songs with that name!
One is an instrumental from 1908 by Duane Crabb. Another was a song by George Hamilton Green (picture above). I've also, in googling the phrase, seen images of sheet music for "Fluffy Ruffles Girls Rag," "Fluffy Ruffles A Slow Drag," and a couple others. Fluffy Ruffles were super popular back in the day, I guess! (Or more likely, one of these was super successful, and the others all were trying to piggyback on its success.)
Also, in case you're wondering, Fluffy Ruffles seem to be both a type of garden flower and a type of fern. As well as a rum/vermouth cocktail.
Anyway, regardless of all that, Beck wrote his own verse of "Fluffy Ruffles"... not much to it though except for the rhyme scheme (ruffles / truffles / troubles / rubble / tumble / bubbles).