Best Friends

What does it really take to be someone's Best Friend?
I always imagine Best Friends are like twins or triplets.
They always appear together, study together, eat together, watch movies together, etc.
They would know each other's liking, preferences, hobbies, favourite things, and so much more.

But what I can't imagine is having to tolerate somebody 24/7.
I mean, alot of times I watch movies alone, and I enjoy that, because I just really wanna watch that movie, at that time, so I don't care, I am gonna watch it no matter what.
If I wanna get that jeans in that shop in the mall, I'll get there alone, like seriously.
That sounds quite scary, isn't it?
I would say I am an independant person, and I am self-centred,
that I want to achieve things for myself most of the time.

I have friends, but best friends? I don't think I am ready for one.