What does it mean when you dream the guy you like asks you out?

Usually dreams are manifestations of what you want or desire. If you desire this guy then your unconscious mind is giving you dreams of what you desire to happen. You want to be with this person, but in your real life you are not. Your dreams are giving you a way to be with this person.

If you feel like your dream was inspiring to you, by all means act on it. However, be warned that not all dreams are prophetic.