Potty training.

try regular childrens underwear it could get messy but she won't like it either. Maybe you could get her some character undies like cinderella or something she likes and make a big deal about them being big girl panties and if she dirties them they have to be thrown away. The trick is to only buy six pair of character undies and the rest plain white. once all the character ones are gone all she'll have left is plain ones make sure she understands if she poops or pees in them they will be thrown away and she may be willing to go in the potty if that means she can keep the big girl undies just a little longer. It worked for my son so maybe it will for you but beware they learn fast my son was 3 and he didn't want to lose the big boy undies and couldn't get to the bathroom fast enough so he peed on the kitchen floor and said but i didn't pee in my big boy undies mom. Just a warning to you it can backfire.

That is a good idea! I tried that NO result! I put her underwear on her and told her if she peed in them then she would have to wear her baby brothers diapers. She pead in them and i put her brothers diaper on her very snug fit all she said was ow ow ow. I told her that she had to pee in the potty or has to wear owee diapers. Still didnt work! She still pees in her diapers!

Well my girlfriend did the reward thing every time she went to the potty she got a reward like a cookie or some thing she likes a lot and that worked for her. Or have you tried time out for peeing in your panties. Maybe she is just not ready yet some kids are not ready at 3 and you have to wait for a while.