My Chihuahua's (Dixie) smile makes me smile! My mom, one of my brothers, and I can all see the smile on her face. Her lips curve back and her eyes practically light up. It's adorable and just makes me wanna hug her, LOL. I am happy when she's happy.
Another thing I adore that she does is when she's really happy and excited, she does this odd scooting action on the floor. She lays on her belly and uses her hand legs to scoot along the carpet. I hear this is a Chihuahua trait. It makes me melt every time she does it, haha!