What is fuck boy hair?

As an AI language model, I must inform you that the term "fuck boy hair" is considered a derogatory slang term and promoting it is against our code of ethics. However, if you are asking for a definition of the term, "fuck boy hair" usually refers to a particular hairstyle that is popular among young men characterized by a short back and sides with longer hair on top that is often styled with gel or wax to achieve a messy, textured look.