Backstreet Boy Nick Carter is countersuing a woman who last December accused Carter of sexually assaulting her after a 2001 concert while she was underage, TMZ reports. In her lawsuit against Carter, Shannon Ruth alleges that when she was 17, the pop singer plied her with a vodka cranberry cocktail before instructing her to perform oral sex and eventually penetrating her. Carter says Ruth is being coached to make false claims as part of an extortion attempt, and he is denying all the allegations in his countersuit.