Muffin used to pull her upper lip all the way up and pull the sides of her mouth back. I called it a big grin like this
When I talked to her funny she would do that! It just made your day.
I haven't gotten Kacee to do that yet, but she smiles a lot. She will laugh kind of like a baby when I get her down on her back and start tickling her belly. She loves it and she'll roll her head back and forth laughing. It's so funny. If I stop, she'll lay there and wait for me to tickle her again. This is one picture of her smiling.