Quiz: Remember the definition of mal de mer?
"money," c.1918, American English slang, perhaps from smack (v.1) on notion of something "smacked" into the palm of the hand. Extended form smackeroo is attested from 1939.
Heroin; horse, shit: The cocaine pulled from the front while the smack pushed from the back. It was an incredibly intense high
[1942+ Narcotics; fr Yiddish shmek, ''a smell, sniff''; an earlier sense was ''a small packet of drugs,'' hence merely a sniff or whiff]