The mark of Cain
for what you've done!
Abel's brown bread
Cockney Rhyming Slang combines the Cockney accent with rhyming phrase replacements. For instance, "brown bread" rhymes with "dead" and thus becomes a replacement. Sometimes the phrase is truncated as well, hiding the rhyming word. "Butcher's hook" is a replacement for "look" but is often just said as "butcher's." So "have a look" becomes "have a butcher's."
Park, Keith. Bible Stories in Cockney Rhyming Slang. Jessica Kingsley Pub, 2009. ISBN 978-1843109334.