My sister seriously embarrasses me. Do you think that's wrong?
Depending on your answer, I'll let you know. What's she doing?
She acts vulgarly and has no sense of appropriate behavior.
If she's acting like an ass in public or something, you're not accountable for her actions. Let your parents know about her behavior.
She's just young and will grow out of it.
Okay, that part I understand. I'd say just have patience and support your sister.