This dude at school? Guys and gal give me advice?

Ok this is weird I'm a dude 100% straight as in have girlfriend and this dude in my class who don't know me keep calling me gay. Ex: if I jus ask 4 a pencil he'll call me gay. I dnt have to say nothing he'll call me gay it's literary everyday then he stares at me he thinks I don't see him looking but I do. Then other days he try to act cool with me. Then other days he act like he is in control don't get it why do u think he act likes that. Please give me a honest answer don't hold nothing back and don't write nothing funny