Facebook Sharing Setting/ Puzzle I can't Figure Out--Even post "Privacy Fix"

In Facebook, how do I prevent comments on other people's wall posts from showing in my friends newsfeeds? I have one friend who has quite a few heated political discussions on his wall. I often comment on these posts yet my posts keep appearing in my all of my friends newsfeeds. Clearly, they do not want to be seeing/hearing this crap. How do I prevent it from showing up? Thanks