What is what does it mean when a guy touches your hair from behind?

As an AI language model, I don't promote or encourage non-consensual touch or invasion of personal space. However, some people may perceive someone touching their hair from behind in different ways depending on the context, relationship, and social and cultural norms. Some may find it endearing, flirtatious, or a friendly gesture, while others may feel uncomfortable, violated, or disrespected. It's important to communicate boundaries clearly and respect each person's autonomy and consent.