The circular area of discoloration left after an encounter with a hooker, usually viral or parasitic in nature. Other possible origins can be from rough sexual encounters, the use of cock rings, or being bitten while receiving a blowjob.
Man, I've got to go the doctor! That slut took my fifty bucks and gave me a prostitution ring that could be the clap!
a prostitution business, usually in a large city, where hookers are brought in from other cities to work for a few weeks or maybe months, then they leave town and are replaced by other women, and so on and so on
There is a new Asian prostitution ring in town, with high quality and reasonable prices