I mean I think it depends from person to person, I do think the teasing thing but to a certain extent. Like if a guy plays with your hair or jokes around with you at your desk in school (you all know what I’m talking about) it’s definitely flirting but the whole liking thing I feel is really up in the air. I think if a guy really liked you the sure sign would be either him initiating conversation / interaction in anyway or his friends trying to call your attention to it if he’s too shy.