E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Sly-Boots.
One who appears to be a dolt, but who is really wide awake; a cunning dolt.
1
“The frog called the lazy one several times, but in vain; there was no such thing as stirring him, though the sly-boots heard well enough all the while.”—Adventures of Abdalla, p. 32 (1729).
