I quite often write out a whole comment pointing out the error of someone's thinking, or just lashing out in general, then realize that I'm not actually adding anything, the person won't listen anyhow, and I'm just wasting my time, others' time, and being negative.

So I click 'back' on my browser and it goes away.

Since I learned to do that, my time on sites like HN has been much more rewarding.