1. You look across the room and crack up at each other.
2. All of your memories in the friend group include the two of you, and if you’re being honest, half the time you were over in the corner by yourselves making fun of people.
3. At least three times a day, you Gchat one another to A) talk shit about your other friends, B) send each other links to weird GIFs, or C) complain about your respective jobs and love lives.
4. If you go an entire day without hearing from them on some form of social media or texting, you start to wonder what’s wrong, and may even call them to confirm that they’re still alive.
5. You often wander off into inside-joke sessions when everyone is hanging out, much to the chagrin of all your other friends who don’t know what things like “foghorn sound” or “oompa oompa” mean.
6. You’ve been together for so long that you occasionally have strange public arguments that no one else understands, but no one thinks anything of it, because they know it will blow over in about 10 minutes and you’ll be back to laughing about some dumb inside joke.
7. On more than one occasion, you have helped out the other one’s ACTUAL significant other when it came time to picking a birthday or Christmas gift.
8. When a new SO comes around to meet you, it’s a much bigger deal than meeting the parents.
9. Your Facebook wall postings are completely incoherent to anyone who isn’t the two of you, and if you looked at the wall-to-wall (is that still a feature?) it would tell the story of two people who are completely out of touch with reality shouting at one another.
10. You’ve gone on multiple vacations together, and properly bickered like an old married couple.
11. “Oh yeah, them… Yeah, I don’t know,” your other friends will often say when a new person asks who are those two people standing in the corner by themselves.
12. The two of you have a very limited concept of “public” and “private” when it comes to your discussions together.
13. There are a few foods that only the two of you truly appreciate — for anyone curious, ours are Hot Fries, cream of crab soup, and this Szechuan dried beef dish — and you have had many near-spiritual experiences either eating the food together or talking about the times you’ve eaten the food together.
14. You sometimes can’t quite remember how you actually met, there was just pre-BFF era and post-BFF era, much like Jesus.
15. When it comes time for actual weddings, you consider one another your +1s, and if you’re not going to go together, you’re definitely going to live-text one another all the gory details.
16. When you’re with them, you know you can just put on a pair of sweatpants, eat as much as you want, and watch hours upon hours of terrible television.
17. The two of you have stayed home from important social outings before to have “a quiet night at home” which mostly consisted of browsing the internet for funny videos together and maybe finishing a bottle of wine.
18. You often laugh yourselves into tears when a whole group of you is hanging out, and everyone just kind of stares at you while you try not to pee yourselves.
19. Multiple people have asked you “so when are you going to get married?” and to be honest, you’ve considered the tax benefits at length.
20. Through many different relationship eras, the two of you have been there, and whenever one of their particularly bad SOs finally left you gave them that look of “Yeah, bitch, get out of here. I never liked you anyway.”
21. Even though you have had your arguments, there is just a baseline of love and understanding that you come back to, and sometimes you honestly wonder why so many actual romantic relationships can’t have that same foundation. 
