Guys: what makes you consider a girl a best friend?

there are these two guys, and both of them are my friends, and they are good friends with eachother, too. i've decided that i want them both to consider me a really good friend so we can be like a really close trio or something, but how do i make a guy consider me like a best friend?? i dont want to date them, and we already have the friendship part down. we talk on the phone, AIM, we live in the same neighborhood and sometimes visit eachother, ride the same bus but i dont talk much on it, have the same lunch pd and eat together but they talk about football so most of the time i just sit there, so they still aren't as close as i'd like them to be. i am kind of quiet, and they are more outgoing and witty, so how do i establish a tighter bond??? they talk about football a lot and im lost... guys, if you have a girl best friend, how did she become your best friend and not a love interest? remember: i'm a quiet person but i want them to consider me a best friend... how do i let loose??