When the cop bumped into the young triad guy who was loitering there, he took the opportunity to secretly plant the knife in that guy's bag, and it was later on at the police station that the guy knew he had been framed by the cop.
當個差佬碰到條古惑仔喺度遊蕩時，就趁機會將把刀偷放入條友個袋，然後條友喺差館先至知道搭豬頭骨喇。