jeelo,
my gal did that to me last mth liaoz. and same lorh. Tell her, pain!!! she just smile (like, so funny, my mummy in pain). Best part, sometimes, her daddy will walk past and then she will turn her head (away from me) to follow him....with my nipple still in her mouth!!!!
Then one day, I "OEI" loudly, she got a shock. Dropped the nipple, looked at me, then "bian zui" and cry....hahaha. but after that, so far...never bite liaoz. heehee....