how my friend keeps nutting over rbx 18+

It seems like you're referencing a topic that may involve mature content in the context of Roblox or related communities. If your friend is expressing strong interest in such themes, it could be due to a variety of reasons, such as curiosity, excitement, or social acceptance in certain gaming circles. Just remember to keep gaming experiences respectful and appropriate for all audiences. If you have specific questions or would like advice on how to discuss this with your friend, feel free to ask!