E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Toad-eater.
At the final overthrow of the Moors, the Castilians made them their servants, and their active habits and officious manners greatly pleased the proud and lazy Spaniards, who called them mi todita (my factotum). Hence a cringing officious dependent, who will do all sorts of dirty work for you, is called a todita or toad-eater.
1
Pulteney’s toad-eater. Henry Vane. So called by Walpole (1742).
