Danish to English Art/Literary Mining & Minerals / Gems

I am translating into Catalan the film "Store Forventninger", based on the novel by Charles Dickens. At one point, Pip (the main character) and his friend Biddy read this poem:

Da jeg kom til London by
Faldera la la
Faldera la la
var jeg saa grumme
Faldera la la
Faldera la la

And after reading the poem, Pip asks Biddy:

PIP: -Hvordan kan du **finde ud af alle de faldera'er**, Biddy. Hvordan er du blevet saa forfaerdelig klog?

BIDDY: - Det ved jeg ikke. Det kommer af sig selv, ligesom hoste!

The piece between ** is giving me trouble. I think it means she has just made up this poem but I do not want to follow the hunch without confirmation...

Thanks in advance!
Maria