According to Spike Lee, from his Bad 25 documentary, "Shamone" "isn't just a cool way to say "come on," but MJ's tribute to soul singer Mavis Staples, who used it in a live version of "I'll Take You There" in 1975."
The name used for money that is acquired illegally, or through under the table offers. Hence the "Shhh" sound emphasizing the fact one must being quiet about how they recieve the money; when acquired, calls for a dance, usually the Shmoney Dance
Shamone comes from the Michael Jackson song "Bad" released in 1987. It is a distinctive deliberate mispronunciation of "come on" used frequently by Jackson, occasionally spelt "cha'mone", "jamone" or more commonly "shamone".
Today shamone can be used pretty much the same way "word" is commonly used.