How do you go about breaking the cycle of treading on egg shells with your friends?

Do you have any friends who are particularly moody or sensitive and is there a way to deal with it that I am unaware of?
It seems that these people pick anything at random to get upset about, thus launching into passive-aggressive attacks on innocent bystanders.
So many of my friends are like this that its making me weary…maybe I should just get some new friends >.>