Is he consistently making fun of you in a rude manner and encouraging other people to do so? Does he see you become upset about his comments, but continues to do this to you? If so, he's being deliberately nasty. If a guy teases you in a light manner (not saying very mean or hurtful things) on occasion, but usually is friendly and actually talks to you, he may be interested in you. Well, if he goofs on you about bumping into the wall then he's playing around with you. If he makes fun of any part of your anatomy or the way you dress then he's being a jerk. You should not feel insulted if he's joking with you, you would laugh along with him.