Some enemies don't give up there dogtags like how i said below. When you point your gun at the heads of certain guys,they say"If your going to shoot,then shoot."With these guys,u need a gun(not a tranquilizer)and shoot him in the arm or leg. DO NOT shoot him in both arms or legs,or he dies! After the shot, hold it to his head and theres your or rather his dogtag. Note: To get the boss dogtags like fatman or olga, just pick them up and then drop them and the dogtag falls out.