Stripper or slut-in-a-box worker. Mostly you hear the
expression from old gomers nowadays. From the old usage of "sling" to mean
delivering or
presenting, so in 30s hep jive, waitresses were hash slingers, bartenders were booze slingers, and so on.
Grandma got through the first part of the
Depression slinging milk, but the dairy went bankrupt, so she slung hash for a while, till she
found out she could make a lot more at the burly-q as a tit slinger.