Dead Horse

Another pecular Australian expression, for 'tomato sauce'



Origins:

There's very little information about the origins of this saying however most reports agree that Australian rhyming slang had its origins in Cockney rhyming slang (from 'mother' England), and contrary to common understanding, rhyming slang was not introduced to Australia until the late 19th century ('common knowledge' has rhyming slang being brought over by the original convicts), as evidence suggests that Cockney rhyming slang itself did not appear in London until the early-mid 1800s.



That said, most pundits believe that the particular phrase of dead horse is such a classic rhyming slang (with literary examples from 20th century) that it was one of the early adoptions of rhyming slang. Which makes it in some ways one of the more interesting ones, as it has not noticably evolved over the last 100+ years.

References:

• Wikipedia - Dead Horse
  
• Wikipedia - Australian rhyming slang
  
• Australian slang dictionary
  
• Reference.com - Australian words