1. You will always be honest with each other – BFFs tell it like it is.
2. Having said that, there's a way to deliver the truth in a delicate and thoughtful way. You look after each other's feelings.
3. You never leave a drunk friend on her own.
4. You trust each other in all situations, even when you're being a sloppy drunk. You won't set each other's hair on fire or draw penises on each other's faces.
5. You also know exactly what she needs when a killer hangover kicks in. Get me some ice-cold water and a bacon sandwich STAT!
6. You can sense when your BFF needs you to hold her hand.
7. You know her brain inside out – you could order for her in a restaurant.
8. You go to each other for medical advice, no matter how gross your problem is.
9. You share all your sexcapades, no matter how awkward they are to tell.
10. You hold each other's hair back when you're ill.
11. All big moments are celebrated through the medium of dance.
12. But your true dance potential is unlocked when it's just you two dancing in your room together.
13. Friends do not flirt with each other's significant others.
14. Or each other's exes.
15. Try not to befriend the ex's new partner either.
16. Ultimately, you despise anyone your BFF despises.
17. You keep all of each other's secrets.
18. You know the full extent of each other's romantic histories, the highs and the lows.
19. You'd never invite your friend's enemy over to a party without checking it with her first.
20. You only post flattering pics of your friend online.
21. Although receiving a double-chin Snapchat instantly lightens up your day and you always reciprocate.
22. Any unflattering selfies you do post have to contain the both of you.
23. You like all of her Instagram uploads and new profile pics.
24. You have full access to each other's closet, but you hold off on borrowing new purchases until your BFF has worn them first.
25. Before a date it's customary to provide a pep talk before and give a full debrief after, plus you need to know she got home OK.
26. You are never not on call as a BFF.
27. No girl has to frequent the bathroom on her own.
28. Diets are there to be broken, ideally together.
29. Nudity is totally acceptable and seeing your friend naked doesn't phase you.
30. Break-up survival plans will be implemented in case of heartbreak; these most likely involve eating all the ice cream and dancing furiously.
31. You don't hold your tongue if your friend is falling for an asshole, but you respect all her decisions, even if you don't fully agree with them.
32. If there's something bothering you, it's better to have a big argument about it rather than keep it from her.
33. You cry unashamedly in front of each other.
34. You are her protector when it comes to warding off creepers on the dancefloor.
35. You step up to the wingwoman plate when needed.
36. You don't cancel on each other last-minute.
37. You ditch whatever plans you have if your BFF needs you.
38. You challenge each other, but you don't compete.
39. You coordinate your outfits.
40. You'll always let her know if there's something stuck in her teeth, if there's a suspicious stain on her trousers, or if her breath smells, but in a subtle, classy manner, of course.
41. You don't do bitchiness – you're too busy being awesome together.
42. However, when a bitchy thought pops into your head, you share it, and she'll probably have the same thought because you basically share the same brain.
43. You help each other out career-wise.
44. When something is bothering you, you don't just say: "It's fine, whatever."
45. You split the bill.
46. It's OK to bombard each other with emails and text messages – you accept each other's crazy.
47. There's no limit to how much you listen to her same story over and over again. You're there to help her work it out.
48. You are each other's ultimate ego boost – you know exactly what to say to keep her spirits up.
49. If you've found a new beauty hack on Pinterest you'll share it with her. You're also allowed to use each other to test new braiding techniques, homemade blusher, and adventurous yoga moves.
50. You can exchange a thousand words in just one look.
51. You climb into each other's beds without asking for permission.
52. And lastly, you have each other's backs. No matter what.