Okay. If you really really must know, frabjous days (orthography notwithstanding) hails from Jabberwocky, a poem of nonsense verse awash with portmanteau and imaginary words by Lewis Carroll, found in his novel Through the Looking-Glass, and What Alice Found There. I don’t have a favourite poem, but this comes closest. With the right motivation, I might just be persuaded to recite it to you.
And, yes, looks like I’m attempting to start blogging.
I don’t know why either.