Purposely Embarrassing Your Kids

My sister is pissing me off. She goes out of her way to embarrass her kids. Her son for example is nearly 18 and back when she was with an extremely abusive guy he beat him so bad that he has night terrors about it and sometimes has accidents at night. When she was going through laundry I the living room with all her friends plus me she held up his sheets saying " Uh oh looks like someone had another accident!" She laughed and my nephew look mortified. Another time with her daughter, we were at a family gathering and my cousin goes "something stinks" he's a guy btw. And she says loudly " Probably my daughter's vagina. She's got a yeast infection". That poor girl is 14. She likes to tell her kids friends embarrassing things about her son peeing the bed. Or make jokes saying her daughter's flow is so heavy because her vagina is so big. Who fucking says that. I told my sister that's not ok and she says I'll understand when I have kids.how embarrassing them is fun. Parents plz explain to me how this is fun or funny or cute?