John Camden Hotten, The slang dictionary
“ Eat his head off. A horse who is kept idle in the stable is said to EAT HIS HEAD OFF. Of late the phrase has been applied to servants who have little to do but constantly “dip their noses in the manger.”Eavesdropper, a listener. The name is derived from the punishment which, according to Oliver, was directed in the Lectures, at the revival of Masonry in 1717, to be inflicted on a detected Cowan [g. v.] , and which was“To be placed under the eaves of the house in rainy weather, till the water runs in at his shoulders and out at his heels.”—Mackey’s Lexicon of Freemasonry. ”
