My science teacher called me flat?

I was in my physical science class and me and my friends were messing around. I hit her chest and my science teacher told us that hitting the chest can cause breast cancer. And my friend jokingly said that she'd hit me back so I'd get breast cancer, and my teacher said "well to do that you need to have breasts first". My friends all laughed. I didn't. I suppose it was funny but all and I'm being a bit sensitive, but, isn't that an odd joke to make? Idk. I am very insecure abt my lack of curves so maybe I'm just being a sensitive baby.