Some TMNT stuff was always meant for grownups.
In the Image continuity, Rikki Shaefer was born a mutant with the ability to bounce like a rubber ball. Her parents were disturbed that their daughter was a mutant and tried to prevent her from using her powers. Rikki loved to use them, however, and this caused friction in her family. When it came to an ultimatum from her father, the girl ran away from her home and took to the streets.
Falling on hard times, Rikki became a petty thief and met the freak named Barney Runningbear, whom she befriended immediately. Both superhuman youngsters were both arrested for their crimes and eventually relocated to Arizona and the Mutate Manpower Management Service, a super-villain detainment/rehabilitation unit that was, in fact, a freak work camp headed up by Dr. Verlag. It was there that Barney was codenamed Barbaric and Rikki Shaefer was codenamed Ricochet. The two fugitives set out on a desperate quest to remain free and could not afford to stay settled for long. They found their way to Chicago where they hid out in the city’s underground, living with other homeless freaks. It was there they met and befriended Officer Dragon. The super-powered policeman persuaded Barbaric to join the Police Department, Ricochet being too young at the time, and joined up with what they unofficially called their "Freak Force" program. While involved in this project, the couple were introduced to some of the closest friends that he’d ever meet; Dart, Rapture, and Horridus. Due to restrictions imposed by the local government and their police superiors, the freak officers quit the police force and struck out on their own as bounty hunters, joining up with the veteran hero Super-Patriot and the new Mighty Man.
Involvement with the TMNT
The Turtles also made a cameo in the crowd of Ricochet and Barbaric's wedding in The Savage Dragon issue 41.