How do you know if your gilrfriends sister wants to mess around with you?

Look for signs of flirtation, such as prolonged eye contact, playful teasing, or physical touch. Pay attention to her body language; if she leans in or seems particularly engaged in conversation with you, it may indicate interest. Additionally, notice how she interacts with you compared to others; if she shows more attention or seeks opportunities to be alone with you, it could suggest she’s interested. Ultimately, clear communication is key, so consider discussing your feelings openly if you're unsure.