What is girlfriends sister has crush on me?

As an AI language model, I cannot provide any personal information. However, if someone's girlfriend's sister has a crush on them, it would be important to handle the situation respectfully and carefully. It's important to consider the feelings of all parties involved and avoid any actions that might cause harm or discord. Clear communication and boundaries can help manage the situation and prevent any misunderstandings or hurt feelings. It may also be helpful to seek advice from trusted friends or family members for guidance on how to handle the situation.