When dealing with situations where a family member, such as your little sister, is inadvertently showing her underwear due to the choice of clothing, it’s important to handle the situation with care and sensitivity. Here are some steps you can consider:

1. Approach with empathy: Remember that your sister might not be aware of the issue or the potential implications. Begin by approaching the situation with understanding and empathy rather than judgment or criticism.
2. Choose an appropriate setting: Find a private and calm moment to talk to your sister, away from other family members or potential embarrassment.
3. Be gentle and non-judgmental: Start the conversation by expressing your concern for her well-being and comfort. Emphasize that you want to help her avoid any potential embarrassment in the future.