or Dicky. A donkey; anciently called a Dick-ass, now termed Jack-ass. It is a term of endearment, as we call a pet bird a dicky-bird. The ass is called Dick-y (little Richard), Cuddy (little Cuthbert), Neddy (little Edward), Jack-ass, Moke or Mike, etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894