How do I handle a coworker who gave me something and will not let it go?

I lost a bunch of weight and last year a coworker gave me a bunch of jeans and shorts to wear that she could no longer fit into. (they were to small for her). Almost every single day since then she has made remarks in front of other co workers about giving them to me. she says things like look at those nice shorts I gave to her or don't they look nice on her? that kind of stuff. I have over looked it even though it really gets under my skin.

But now she is loosing weight and is saying stuff like I don't have any good shorts I gave them all to her. and has now even said today that if I loose more weight that she want me to give them back to her.

If i had the money (I don't) I would go buy me some shorts and bring hers in and throw them at her. I am so offended by this. I gave my clothes to a coworker also the ones that are to big for me. I have never mentioned it to anyone even when that coworker wears them I say nothing. Because to me once you give something away its no longer yours and you should not brag about giving them away either. I need some advice on how to handle this girl before I just blow up at work on her one day soon.