Butters' Bottom Bitch

"Butters' Bottom Bitch" is the ninth episode of the thirteenth season of "South Park". It first started on the Comedy Central in the United States on October 16, 2009.
In this episode, Butters pays a girl $5 to kiss him on the playground. He decides to start a business, a "kissing company." This is a parody of prostitution with Butters as a pimp. Police officers hear about Butters' company and think it is a real prostitution ring. Sergeant Yates disguises himself as a female prostitute to find out. 
Other websites.
Episode's official page