Spit Feathers Meaning

(idiomatic) To feel very angry; to sputter angrily.

Example: 2003, Robert David MacDonald, "Salto Mortale" in Plays Two, ISBN 9781849439794, p. 94 (Google books view):
  Where is that sodding drink? I'm spitting feathers.
2003, M. Dylan Raskin, Little New York Bastard, ISBN 9781568582740, p. 202 (Google books view):
  I was just about spitting feathers. My throat was so dry and sore that I could barely feel my own tongue.
2010, Peter Bond, Exodus: Earth Fights Back, ISBN 9781609111687, p. 135 (Google books view):
  â€œI've always liked camomile tea, and I'm spitting feathers after walking all the way over here. Nothing quenches the thirst like camomile tea.”
2007, Imogen Edwards-Jones and Anonymous, Fashion Babylon, ISBN 9781416543183, p. 19 (Google books view):
  He is high as a kite on Fair Trade espressos and spitting feathers that Ted Nicholls is apparently having some sort of comeback.
2011, Jonathan Wright, Heretics: The Creation of Christianity from the Gnostics to the Modern Church, ISBN 9780547548890, p. 258 (Google books view):
  Yesterday's heresy—the sort of thing that made orthodox theologians spit feathers—becomes today's tourist attraction.
2012, Tom Bennett, Teacher: Mastering the Art and Craft of Teaching, ISBN 9781441114358, p. 43 (Google books view):
  Spartan education was entirely geared to the sublimation of the individual to the state, the disintegration of the ego and its reorientation as an agent of Spartan civilization. Proponents of child-centred education would spit feathers, I imagine.