Great mistake—Make up your mind and don't shilly shally.
-- Agatha Christie, A Caribbean Mystery, 1964
But look, Your Highness, I didn't come to shilly-shally, so don't say anything to inhibit her. I want it straight.
-- Saul Bellow, Henderson the Rain King, 1959
In the great tradition of reduplicating a phrase to infuse it with a dose of levity, shilly-shally comes from the phrase “shall I, shall I.” When shilly-shally first entered English at the turn of the eighteenth century, it was spelled "shill I, shall I."