Ouch, that hurts...

Just a second ago, Lydia grabbed my nipple in her little fist and twisted. I said, "Ouch! That hurts Momma!" and tried to make a sad face. She looked at me soberly for a second before bursting into a big smile. My question...was she trying to lessen my pain by flashing her gummy smile, or (more likely) is my sad face just too funny for her?