I think your question was more about pouting than whining...
What has worked for us:
Remember that pouting happens because the child is feeling sad or angry about something. Firmness and consistency are absolutely necessary, but we found that scolding or reprimands, in the midst of the situation, often increase the negative emotions rather than decrease them. By making a child more upset, it is unlikely that he or she will be able to simply "turn off" the pouting.
Instead, we focus on ways to impower our children to solve the problem. In other words, when they feel the need to pout, we affirm that they are feeling upset, but suggest they figure out something they can do to make themselves begin to feel better. We used the catch phrase "Let's make a plan!" This phrase was so exciting to our DD, for some reason. Just the idea of "making a plan" seemed grown-up and important to her. When she began to express a negative attitude, we said that we could work together to "make a plan" about how to feel better. After modeling this a few times, she knows what we expect. This strategy puts the ball in her court and requires that she take action to
do something more positive. (Instead of just "stop doing
that", it helps her begin to think about better things she could do instead.)
Much to our surprise, she comes up with great ideas! She decides to take a walk, draw a picture, talk to someone about the problem, begin a new activity, etc. Many times, she simply realizes that there is a very direct way to solve the problem that upset her. This is not a game of "what can I get for pouting" -- (e.g. "a piece of candy would make me feel better" or "I want to get my way") -- but a strategy that requires that she begin to find ways to get past negative feelings, accept the situation as it is and take action to move on.
She feels really good about herself when later we can say to her, "When you did ____, I noticed that you seemed to feel so much better. That was a really great plan!" She feels a real sense of ownership over her "plans".
Now, when we are out somewhere and she gets upset, we can simply say, "Why don't you take a moment to make a plan? I bet you can figure out a way to feel better about this."
I know it sounds a bit cheesy...but it has really worked!
