I am a sophomore for my younger brother and a freshman for my younger sister. What should I do if I find my sister and boys like this today?
You must be embarrassed to tell your sister about this, then find an elder or teacher that your sister admires and trusts, and tell your sister that as a girl, she should have a sense of self-protection. Usually keep a certain distance from boys and try not to be alone, otherwise you will only get hurt. It is best to adopt this method.