Everyone is busy during the holidays, and it sometimes causes tempers to flare in a way that they normally wouldn't. No matter how frustrated you get with anyone you work with, never (ever) yell at them. If you have made the mistake of yelling at a co-worker or someone you supervise, make sure to have a normalizing conversation as soon as possible, and be sure to apologize for your behavior. Then demonstrate your apology in action by never doing it again.