The actual reason why BFF and I are BFFs is that she saves my life several times a week, and she knows this. But here is a less sappy anecdote, which I offer as evidence that we have many of the same quirky interests:
Katrina and BFF are having a conversation about lesbian activism, which is ok, even though they are heterosexual. This reminds Katrina of something--
Katrina: Hey, BFF, I just read a story last night by David Foster Wallace about lesbians and Jeopardy!
BFF: I read that story!
BFF: Yes, in high school, in literary club.
Katrina: What are the odds?
Weird, huh? Thanks for everything, BFF!