1. You know her entire wardrobe by heart.
2. You are consistently available via iPhone. To yea or nay potential clothing purchases.
3. You tell the truth about whether she looks good in something or not. Without worrying she'll be offended.
4. You can refer to each others' "eras" and know exactly what the timeframe was. Like "my slutty period," "your Dressing-Like-Taylor-Swift era," "my dating-only-douchebags stage."
5. You have switched off being the Blair and the Serena of your friendship. Multiple times.
6. You know super-intimate stuff about her boyfriend that makes it difficult to look him in the eye.
7. You are never not in text communication, even about the dumbest things. Lots of "lolololololz." Nobody sounds like they're getting their master's, that's all I'm saying.
8. You have FaceTimed each other from your respective apartments while eating.
9. You've asked her incredibly personal questions about the state of your genitals without shame. "Is that normal?"
10. You've seen her naked and crying. And vice versa.
11. You've seen her throw up in a bar bathroom. And vice versa. :|
12. You could list all of the people she's ever slept with, chronologically. And possibly one or two she forgot about.
13. You've slept with, or at least made out with, one person in common.
14. If you live in different states, you FaceTime while you're getting ready to go out because it feels like ~*~*cOlLeGe~*~*~.
15. By the time you're in your mid-20s, you both have an "it's like the time…!" for every situation.
16. You have some weird memento of your friendship in your apartment that freaks your boyfriend out. But he could never possibly understand.
17. Her mom posts on your Facebook wall. Viral cute kid videos, mostly. And the occasional unsubstantiated political claim you don't agree with.
18. Even if you haven't done some specific sex act, she went into so much detail the morning after she did it, you kind of feel like you have. I know everything about anal. #bff
19. You watch the same shows at the same time just to talk about them. And if she's not caught up with you, it's torture. GODDAMMIT, JUST FINISH NASHVILLE, JULIE.
20. They've had one or more of your articles of clothing for at least a year. They're her J.Crew cords now.
21. You always owe each other like $20 but neither of you are really worried about it because the IOU has been floating back and forth for years.
22. You know you'll give killer wedding toasts for each other. And you regularly make mental notes of jokes to include.
23. You talk about your pooping habits all the time.
24. You have hungover brunches the morning after parties just to do post-party recaps.
25. You think her hair looks best however it is naturally. I don't always feel like my curly hair suits me, but she insists it's prettier than the blowouts I occasionally get.
26. You talk about each others' boobs a lot. And touch them.
27. You're completely unselfconscious when carbo-loading or ice cream binging around each other.
28. You remember all her Facebook pictures and have a favorite. It's probably one you're in. One of many.
29. She'll put up a BFF selfie on Facebook even if she looks bad, as long as you look hot.
30. You can tell when she doesn't like someone even when it's really subtle.
31. And you instantly know exactly why the person bothers her.
32. Sometimes when you meet new people they can't follow your conversation because you pretty much communicate in half-sentences and glances.
33. You're together so often other people have given you some kind of joint nickname.
34. You don't think twice about speaking on behalf of each other. "Gena doesn't like olives on her pizza." :D
35. Her's is the one phone number besides your mom's that you have memorized by heart.
36. You have written actual, old-fashioned MAIL LETTERS to each other before. LIKE IN HARRY POTTER. #OWLING.
37. You use "we" when talking to other people the way couples use it. "Oh, we love that place!"
38. You have restaurants/bars/places that you can't go to without the other without feeling like you're cheating on her. See "that place," above.
39. You know all of her social media passwords. "If I die, can you shut my Facebook down for me?"
40. Your parents always ask how she's doing. She's the only friend of yours that your dad can remember by name.
This post originally appeared on Cosmopolitan.com.