wait untill u see him with it hear about him with it . when u have even slightly somehting linking that guy to your mp3 player such as someone sayign to you "yeah i saw that guy nate wiv a mp3 player liek your" thats definate evidence in my opinon! then u go round there asnd fight ....also seeing as its a coke head (sniffing E cos he cant get real coke) hes more or likly gonna have a weapon so the day b4 or a couple of hours b4 u plan to fight him go near to where its gonna happen and plant your self a weapon in a non bate place so if u need to run a couple of steps to grab it its there. if not place his mouth open on the kerb stamp on the back of his head while shouting "NOW SAY GOODNIGHT!"