Lydia invented a game. It's called "I'll be happy and you be sad".
Basically she says.. "I'll be happy and you be sad" and you make a sad face. She makes a happy face and says something like "Happy, happy, happy" while pointing to her mouth and kind of dancing around.
Next she asks you why you are sad and you are expected to give a reasonable kid reason for being sad, like "I miss daddy when he is at work" or "I have a boo boo". (I tried scenarios like "Our utility bill is too high" or "I fear a double dip recession" but she wasn't having it!)
Here is my favorite part. The happy person tries to make the sad person feel better. Lydia will say something like "We can call daddy and ask him to come home for lunch" or "I will kiss your boo boo and get you a band aid." It is SO sweet and fun to see her figure out how to solve the other person's problem. PLUS, when it is her turn to be sad, I get an insight into the kind of things that bother her. It's role playing, empathy, and Lydia thinks it is SO much fun.
I'm not sure exactly how this game developed. She was playing the other day in the car with some older kid friends and they said she made it up. I'm not sure how you would teach it to your own toddler, maybe starting with the grown up making a happy face and saying I'm happy and then ask the kid to make a sad face. If you can get them to play along enough to come up with a reason they might be sad, then I think they would be hooked. Try it out. I LOVE the Happy Sad game.