Spit has 2 meanings
A term describing a person flirting or attempting to flirt; commonly used as "spitting game" in a club setting.
There goes Charlie spitting his game on the foxes at the bar.
|Bootylicious||Attractive with a nice rear end|
|Fox||An attractive woman|
|Swag||Skills or style|
Spit is a term for when a person freestyle raps. This type of raping features improvised lyrics that come from the rapper without any preparation.
Spitting became popular in the 1970s when hip hop was birthed out of MCs dissing each other to the tune of musical beats. The 2002 film "8 Mile" starring Eminem features several freestyle rap scenes where rappers battle each other with their "spit."