Justin Bieber's rapper friend Lil Twist reportedly threatened a fan who took a picture of the singer while they were out shopping.The 'Baby' hitmaker was shopping with Lil Twist and some other friends at a Best Buy store in the San Fernando Valley area of Los Angeles on Sunday (Feb 3) when Justin made time to pose with fans and employees.Although the 18-year-old singer asked people not to take photographs without asking, one overeager fan took a picture leading Lil Twist to step in and cause a scene.A witness told RadarOnline: "Justin asked people not to take photos without asking and said he would pose with anyone who wanted a pic."[Lil Twist] tried defending Justin and got in the guy's face and tried to take his phone. The guy tried to get away and Twist went after him. Witnesses were appalled at what was happening."Twist created a scene."Justin's guard identified himself as part of security and calmly explained that no one wanted to take his phone."The guard calmed the situation after Twist made it a mess."Friends of Justin are worried Lil Twist is a bad influence on the star and believe he is leading his astray.An insider explained: "The guy is not a good influence. Justin needs to find a new friend."