Proverbs 22:24-25 (NLT)
24 Don�t befriend angry people or associate with hot-tempered people, 25 or you will learn to be like them and endanger your soul.

These verses give good reason to be cautious with whom we associate with. In friendship we allow ourselves to be close to others, willing to serve, willing to listen and will to engage with them. But it is our folly if we associate with someone who draws us into their moments of anger and cause us to be outraged for no good reason. While we must be civil to all we can still use caution to decide who we call friend. If a person is easily provoked to anger, becomes touchy at the slightest of comments, and becomes passionate about his resentment of others and cares not what he says then such a person is not fit to be a good companion or friend. In his moments of anger he will expect us to be like him and if we follow that will be our sin.

In his autobiography, Number 1, Billy Martin told about hunting in Texas with Mickey Mantle.
Mickey had a friend who would let them hunt on his ranch. When they reached the ranch, Mickey told Billy to wait in the car while he checked in with his friend. Mantle�s friend quickly gave them permission to hunt, but he asked Mickey a favor. He had a pet mule in the barn who was going blind, and he didn�t have the heart to put him out of his misery. He asked Mickey to shoot the mule for him. When Mickey came back to the car, he pretended to be angry. He scowled and slammed the door. Billy asked him what was wrong, and Mickey said his friend wouldn�t let them hunt. �I�m so mad at that guy,� Mantle said, �I�m going out to his barn and shoot one of his mules!� Mantle drove like a maniac to the barn. Martin protested, �We can�t do that!� But Mickey was adamant. �Just watch me,� he shouted. When they got to the barn, Mantle jumped out of the car with his rifle, ran inside, and shot the mule. As he was leaving, though, he heard two shots, and he ran back to the car. He saw that Martin had taken out his rifle, too. �What are you doing, Martin?� he yelled. Martin yelled back, face red with anger, �We�ll show him! I just killed two of his cows!� Billy Martin was a great teller of tales, and many doubt that this event really happened, but it does illustrate a very real truth. Anger can be dangerously contagious. [Scott Bowerman, Bishopville, South Carolina. Leadership, Vol. 16, no. 1.]