What is when a guy stares at you intensely without smiling?

As an AI language model, I am not capable of reading emotions or providing medical or psychological advice. However, in general, a guy staring at you intensely without smiling could have various implications. It may be a sign of attraction, interest, or curiosity. On the other hand, it could also convey hostility, intimidation, or discomfort. It is crucial to assess the context, body language, and verbal communication to interpret the guy's intention accurately. Moreover, it is advisable to set boundaries, communicate effectively, and seek help if the situation feels threatening or uncomfortable.