Where does the expression “Gentlemen Prefer Blondes” come from and What does it mean?

As far as is known, Anita Loos originated the expression “Gentlemen Prefer Blondes” when selecting it as the title of her book.

But she may have taken the idea from an amusing book, The New King Arthur, which first appeared anonymously in 1885, but was written by an American poet, Edgar Fawcett.

The book is a burlesque of Tennyson’s The Idylls of the King, and in it Sir Galahad, “the spotless knight,” is depicted as an insufferably vain prig.

Vivien, a brunette lady-in-waiting to Queen Guinevere, desperately in love with Galahad, has sought vainly for the magical “face-wash and hair-dye,” alleged to be a secret concoction of Merlin, the magician, for both she and Galahad think that his affection would be fixed upon her if she were a “Saxon blonde.”

Frustrated in obtaining the concoction, she says at last:

Sir Galahad, cant thou never love me, then,
If! remain brunette? I promise thee
That no brunette of more domestic turn
Has ever lived as wife than I would prove.

To which Galahad loftily replies:

Hadst thou been blonde . . . ah, well, I will not say
What joy has perished for all future time!
O Vivien, wildly, passionately loved!-

Vivien: My Galahad! Dost thou mean it?

Galahad: No, not now.
I would have meant it, wert thou only blonde.
Farewell, by blonde that art not nor canst be
This woful barrier lies between us twain
Forevermore. I shall be virgin knight
Henceforth, with one long sorrow in my soul,
And all my dreams and thoughts to one sad tune
Set ceaselessly, “She might have been a blonde!”