How would you feel if another ADULT made fun of your kid's name?

This lady made a joke about our names today to my mom. She's an adult, the mom of my sister's friend. I personally have always hated my name and my sister hates hers and it makes it worse having another adult make fun of it. We all have German or Dutch names cause of our grandparents but we're Americans living in Australia now so they're very very weird here. But we dont go by those names. My name is Katrien and i go by Katie and her name is Hannelie (hahn-a-lee) and goes by Hanna. My mom told this lady our real names and the lady made it a joke about it sounding like Hannah-Lie and her daughter repeated it. She said my name sounded like canteen, it doesnt AT ALL. So now my sister's friend is gonna think its ok to make fun of my sister's name. Idk why my mom told the lady to begin with. I just think its disgusting to make fun of some other kids names when your a parent. Btw the lady and her daughter are fat and not pretty at all and we'd NEVER ever make fun of them for that cause that's just really mean. But she thinks its ok to make fun of US?