I've been working on helping Cate not be a poor sport.
If she wins a game (which she does quite often, but probably because most of the games we play with her have to do with luck, not skill), she's super excited.
If she loses, well, she most often stomps off to her room yelling something like, fine! then you're not invited to my tea party ever again! And then she slams her door which isn't very nice but she's right where I want her so I guess it all works out. (Sheesh. Is she almost 4 or almost 14? Heaven help me.)
So we play games and I remind her of the good things to say. Even if she loses. Good game! Thanks for playing with me. Awesome. Good try! Stuff like that.
We played Candy Land on Saturday. She set up the board. Before we started I talked to her about what it means to be a poor sport (the stomping away mad and slamming the door stuff) and what she can say if she loses. And what she should say if she wins.
And then I asked her, "So what happens if you don't win?" (hoping she'd remember that we say Good game or Awesome or Good try)
She thought for about 2 seconds and said, "You lose."
Baby steps, people. Baby steps.