What to do if…
Your friend is always talking to this guy after school who has a nice car and looks shady. You are worried about them getting into a bad situation.
Consider asking your friend, “who's this?” or “what are you talking about?” Maybe offer to be a safety buddy for your friend and see if they will check in with you after meeting with this person. Tell them you want them to be safe and think they should tell their parents or guardian about this person.