Slang for EmploymentInsurance or Welfare. Derived from the Scottish word "pogie" which means workhouse. A workhouse being a place in the 1500's where beggars, children and others unable to support themselves were sent to work and in turn be taken care of.
The Marines in China before WW II were issued candy (Baby Ruths, Tootsie Rolls, etc.) as part of their their ration supplements. At the time, sugar and other assorted sweets were rare commodities in China and much in demand by the Chinese, so the troops found the candy useful for barter in town.
The Chinese word for prostitute, roughly translated, is "pogey". Thus, Marines being Marines, candy became "Pogey Bait".