Police in central Massachusetts are warning residents to be on the lookout for men who may be challenging passersby to a rap battle.Charlton police said a black SUV with two or three men in their late teens or early 20s inside, pulled up to three young teenage boys on Dresser Hill Road at about 3 p.m. on Saturday.One of the men -- described as having brown hair and a pale complexion, wearing a gray T-shirt, gray pants and open-toed sandals -- got out of the vehicle and started rapping while the other men asked the boys if they wanted to "spit some bars" with them.When the boys declined, the SUV drove off."Although this was suspicious behavior and frightening to the boys, nothing made this appear to be an attempted abduction," Charlton police posted on Facebook.Anyone with credible information about the incident is asked to call 508-248-2250..