red rum
noun
1
a variety of heroin. An allusion to the qualities of the legendary racehorse (steeplechaser Red Rum won the UK Grand National a record three times). Also rhyming slang for 'dumb' and 'murder' spelt backwards UK, 2001.
2
a mixture of heroin, barbital, strychnine and caffeine. Also known as RED ROCK OPIUM from which this may be formed by elision; it is interesting to note with regard to the dangerous nature of this cocktail that 'red rum' is 'murder' backwards UK, 2002