what does he mean by boyfriend?

was he joking? we are in the same friend circke, known him for like 4 years, we sit together in the same lunch table with our friends. dont know y but this year, my friends kept teasing me about me and him. me and him are in the same class, having almost all classess together. he always tease me and play tricks on me,call me names, annoy me, taking away my stuff. i hate him for doing that but he is genuinely a nice person. my friends say that we look cute together, saying that he likes me ans stuff, i think they r not true. at lunch, he said "hi, i am ur boyfriend" and he wanted me to shake hands with him. at that time i didnt think about liking anyone, i think that he was joking. i dont know y but i was angry. what did he mean?