Just be like : "I'd rather not think about that."
Or just think this when this bad thought occurs :"Unbelievable , seriously unbelievable" ((Think of something random , and visualize it like an object or tree or rock , something along those line)) " Actually , actually" ((Change your thoughts while thinking this way and envision something entirely random for example Elephant Ear Plant))
This is a deflection method , once you start to visualize things your thinking about... it should start to quite down , think less with words and try to visualize things like a image, when thinking about things like an image it doesnt usually have voices attached to it , if interrupted by this voice dont lose your train of thought and continue to deflect undesired thoughts and voices.
Definitely if you enjoy legitimate privacy do not do illegal drugs , at all. Once you do a drug it forfeits your right to privacy and you get severely annoyed forced telepathy , repititious nonsense. So , I would steer clear of all drugs if you enjoy privacy.