What is my guy friend calls me boo?

It is possible that your guy friend calls you "boo" as a term of endearment or affection. The term "boo" is often used to refer to a romantic partner, but it can also be used in a friendly or platonic manner. Your guy friend may see you as someone special or important in his life, and may use this nickname as a way to express his feelings. However, it is also possible that he uses this nickname simply because it's a common term of address among friends. Ultimately, the best way to understand why your friend calls you "boo" is to ask him directly and have an open and honest conversation about your relationship.