Parents stalking my facebook, how do I make it stop?

My parents are using some Yahoo tool to stalk my facebook and all my friend's feeds, I already blocked them on FB but somehow they can use this tool to get through. Frankly, what my friends say and do on facebook is NONE of my parent's business, and the fact that they watch over EVERY THING I do and say pisses me off too, say a swear, get in trouble for it, make a post in the early hours, get in trouble for it. Please, someone tell me there is a way to shut them out. All I know is that they're using some yahoo tool to stalk my posts and my friends posts, what is it and how do I shut it down?