E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Manger or Manger le Morceau.
To betray, to impeach, to turn king’s evidence. The allusion is to the words of Jesus to the beloved disciple—he will be the traitor “to whom I shall give a sop when I have dipped it,” etc. (John xiii. 26.)
