I'm a children's counselor specializing in preschool age children (2-5) AND a mom of two boys so I'm coming from two perspectives. At your son's age, he has just discovered recently that he is an individual separate and a part from you and with this developmental realization, he is experiencing emotions in new ways as well as experimenting with this newfound independence and ability to use words. Consider it a very positive thing that he is using words to express his emotion even if the words don't match with the emotion or make rational sense because many two year olds would be biting or kicking to show how they feel. So, he's ahead of the game. What I recommend is you try some "emotion coaching." Consider yourself his coach, his teacher, there to guide him through this pioneer experience his two year old self is having. Get down on his eye level and compassionately reflect the emotion you note, not focusing on the words he is using, "Johnny, I can see that you are feeling really frustrated/mad/sad...." and match the word with the emotional reflection and empathy on your face and in your voice. Here you are reflecting empathically, giving him words to tag his emotion and encouraging him to express. Please go read John Gottman's book Raising an Emotionally Intelligent Child as this will help with this process and provide the scientific research data to support WHY emotion coaching children is SO important....As for "discipline," many parents don't know or don't remember that the word means "to teach" not necessarily just to punish. The purpose of discipline is to help him learn from the experience. Consistency is absolutely key in enforcing consequences that are immediate and somewhat logical to the "crime." If he throws a toy you can calmly but firmly say with great disappointment and even empathy, "Oh, you threw your truck across the room. Toys are not for throwing. When you throw your toys the toys have to be put in the attic/topshelf/basement until after dinner." Time out was not designed as punishment but rather as a breather, a place for a child to be removed from the pleasurable activity to have time and space to breathe and give thought to what he did that was not appropriate. It is not effective with all children. But if it is the only thing you can do, do it calmly and firmly placing him in a designated place away from everyone and completely ignore him (this is called extinction when you remove all attention) and when he comes out you review why he was in time out and then if he repeats the undesirable behavior, you calmy and firmly return him to time out with one statement, "Oh, I see you chose to hit your sister again so you will need to be away from everyone and you need some more time to think about why we do not hit people." I hope this helps.... There is another GREAT book I recommend to all moms and dads called Parenting With Dignity. I'm going to be teaching a seminar for parents on this along with the true meaning of discipline with lots of tools for parents to learn in working with young children in February in Kennesaw if you are interested. Good luck!