Why Does Playing Basketball Make Me Talk Alot?

I'm 19 years old and I am what you call a hooper. I eat sleep and drink basketball. Im real good at it. I'm a real good shooter, Im fast off the dribble, got good handles. off the court I am a real quiet and laid back person but as soon as I get on the court I talk alot and real loud. we had a family get together the other day and I was real quiet until my older cousin mentioned that he can beat me in basketball and then I became the loudest person in the house. why does basketball do this to me?