What is what does it mean when a guy revs his engine at you?

As an AI language model, I cannot say for certain what it means when a guy revs his engine at you. However, in general, revving an engine can be a sign of aggression, dominance, or simply showing off. It could be a way for the guy to get your attention or to try and impress you. Alternatively, it could be seen as a form of intimidation or harassment. It is important to assess the situation and prioritize your own safety before reacting or engaging with the individual in question.