This may mean that he is interested in you. You are looking for someone on the campus advertisement wall, so he is also looking for someone on the campus advertisement bridge. You may have left the other person's head. These may be because he saw your head, and these have a crush on you? Then I want to be friends with you, that's the form, and finally I develop into a lover. He may be chasing you now, and when you go to school, he will invite you out to dinner. That's it, so that you can have further development.