My best friend is being cocky about having a lot of friends on facebook?

[OOooh]

It's pretty immature to be comparing how many friends she has to how many friends you have and throw it in your face that she has more than you. Like you wrote, the number of Facebook friends doesn't correlate to the number of real, true friends. There's an insecurity in your friend where she feels like a larger number of friends on Facebook means she's better or more popular, and this isn't true. Don't let her sense any jealousy. You can make a short comment like "that's nice," and then change the subject. Hopefully she'll get tired of telling you about her Facebook friends. Doesn't she have a life outside of Facebook?