City officials on Thursday issued a new warning about a “dangerous” TikTok trend that encourages teenagers to steal Kia and Hyundai vehicles. The nationwide “Kia Boyz TikTok Challenge” has hit the Big Apple, with thefts of the popular makes jumping last year, Police Commissioner Keechant Sewell said at a press conference with Mayor Eric Adams. “Viral social media videos from last year demonstrated how quickly and easily certain Kia and Hyundai models can be stolen,” Sewell said. “As a result, Kia and Hyundai set rules rapidly in communities nationwide, including here in New York City,” she said. “In response, the…