"Stop Snitching" T-shirts are one of Milwaukee's hottest fashion trends. [...] The shirts' message - interpreted with slightly varying twists - essentially urges people to stop talking to and cooperating with police. [...] But the shirts are fueling more than fashion, police and prosecutors say. They send a dangerous message to others that, if followed, has the potential to "destabilize the whole criminal justice system," according to John Chisholm, Milwaukee County assistant district attorney.