My brothers friends

Umm yeah every since i could remember my brothers friends have always become my friends. and its cuz we can talk about stuff they dont talk about with my brothers. but for any of you that are brothers would bother you if ur sister and your best friends had a friendship that was as strong as or rivaled the strength or ur own. my brothers get pist when me and their friends talk which makes it more fun but i dont have alot of friends other than them and everyone talks crap. like quit flirting and all that. but i duno cuz my brothers friends are my friends and i was just wondering if that bad