1. You don’t bicker like siblings as much as you do like an old married couple (but like family, nonetheless.)
2. You introduce them to strangers as “so-and-so, who is basically my sister/brother/etc.” Calling what you have a mere “friendship” — forget even “best friendship” is a serious injustice to what you got goin’ on.
3. You are mildly dysfunctional together… (and apart.)
4. Your extended families start to intermingle, and all of a sudden you find yourself as closely connected to your best friend’s parents as you are them. They take you out for dinner too, check up on how you are not only when they call their actual child, but when they text/Facebook message you.
5. You start reaching unprecedented levels of comfort. Otherwise humiliating and oftentimes disgusting, you know there’s no front to hold up with these people — so you let live, with complete abandon of the undecided “taboo” of talking about poop like, all the time.
6. You willingly spend your money on them. Not because you’re obligated to get them a birthday gift or because you’d seem rude if you were the only one who showed up to the grad affair sans a check in tow, but because you want to. You start getting care packages from them for no reason at all, gifts just because something reminded them of you, etc.
7. And you don’t just exchange gifts anymore. You start throwing parties for each other, giving each other dinners out and surprise celebrations, cake waiting in the apartment when you get home from work and other total-shit-your-family-would-pull charades.
8. They don’t pretend to be nice all the time. The reality of it is that nobody can be perpetually in a good mood, and those who are are just faking it. Your friends turned family know they don’t have to though, silly things like that don’t really threaten your relationship.
9. If you do get into an argument, you do it like any good old fashioned family does, and proceed to let it blow up one night and then completely forget about it the next morning, and never really speak a word of it again. #Healthy.
10. You print and frame your pictures of one another. And keep them around your home.
11. You check up on each other throughout the day: you text to make sure they’re holding steady after your intense G-chat about your unbearably shallow coworker, the love-of-your-life-who-loves-you-no-longer for the trillionth time, etc. You probably get more “good morning, how are you?” texts from them than you do your actual significant others.
12. Everything is presumably in joint. Party invitations, meals cooked, clothes bought, you don’t do anything without one another.
13. You’re used to them being around so much, it just kind of feels like second nature. Long silences during car rides don’t feel odd, just hanging around and watching TV without necessarily “entertaining” each other doesn’t either — you just hang out, no other pretenses needed.
14. You’re often more nervous about introducing your new love interest to them than to your actual, biological family. (They’re going to be way harsh, you realize. If you didn’t appreciate the “Clueless” throw in there who even are you.)
15. You realize that you’re stuck together forever, and you really didn’t have any other choice anyway. 
