I don't know why Mommy was laughing so hard

Today Mommy took me and Madeline to the grocery store. We were sitting in the cart while Mommy and a nice lady in a red shirt were putting the groceries up on the counter. The lady was talking to me and asking questions. I decided to share an important fact with her, since she was so interested in my life. I turned all the way around so I could face her and said in a very loud and clear voice, "I'm obsessed with painting my lips!"