1. You have so many lame inside jokes from when you were children and know exactly what the other one is about to say just from the type of laugh they're doing.
2. You keep secrets from your parents for each other, because *obviously* you had to tell him you broke the necklace mom got you for Christmas, but there would be hell to pay if she knew.
3. You can happily have a night in together watching stupid TV shows and eating snacks in the same way you would with your girlfriends, only it's better because he literally doesn't care one bit about how you look/smell/behave.
4. But you'd also invite him on a night out with you. You go all Monica and Ross Geller on the d-floor, make loads of hilarious memories together and he'll make sure you get home safe.
5. He will identify every movie quote you could ever throw at him because the chances are you recommended the film to each other to watch and– unlike normal–you actually did.
6. You share an equal love/hatred for family reunions and spend the whole car journey home gossiping about what a douchebag your annoying cousin is.
7. You have nicknames for each other's friends. "Ah, yung parating may man purse? Si Murse?"
8. Any new love interest for either of you is put through their paces just to make sure they're up to standard. And if they're not? Your brother has no trouble in telling you that they're not good enough for you.
9. You have your own language. Whether it features words from when you were little or weird private jokes, the chances are your texts literally wouldn't make sense to anybody else.
10. You just click. Even if you haven't seen each other for weeks, slipping back into each other's company is SO easy because you've got an unbreakable bond.
11. You have "a song" or multiple songs together that will forever remind you of each other and/or something you experienced together–and don't even get us started on the iPod playlists. "So this one time, my brother and I..."
12. He makes you laugh even when he's 50 minutes late and you're trying to be really mad, it's hard to be angry when he's pulling a stupid face or doing a cheeky grin.
13. You're totally honest with each other. Seeing as he's your brother, he's not gonna judge you for drunk calling you-know-who (an ex, not Voldemort) or forgetting about your colleague's birthday.
14. He doesn't like to see you sad and will do essentially anything to make you happier. Buying McDo fries, rom-com movie nights, taking the day off work–you name it, he'll probably attempt to do it.
15. He's proud of you. Whether you've eaten a whole pack of Oreos in one sitting or flew to the moon, you can always rely on your brother to let you know how proud he is of your achievements.
16. You've got a secret handshake. Yes you're in 20s now, SO?
17. You're absolutely horrible to each other but know it's usually just bants or with your best interests at heart.
18. He knows your order at restaurants like it's second nature. Probably because it's been the same since you were 13, but it's still great.
19. Moral support likes on social media are basically the meaning of having a sibling, aren't they?
20. He's the first person you call, whether it's asking for advice about how to change your tire or to tell him you saw Dingdong Dantes at the mall, you know your brother will give you undivided attention like no one else.
21. He doesn't get mad when you steal his clothes to wear as PJs or as boyfriend fit shirts.
22. He always has your back. From family feuds to someone pissing you off at work, you can always rely on your bro to have a good bitch about them with.
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.