1. You can be your most ridiculous selves with each other.
And (pretty much by law) she's not allowed to judge you for it.
2. You have shared childhood memories.
And SO many inside jokes!
3. You braided each other's hair for school every day.
And she even let you borrow her butterfly clips.
4. You share under-the-cover secrets.
Even though you were told to go to sleep hours ago!
5. You can pretty much communicate using only your eyes.
You can't explain how!! You just GET each other.
6. She is always there when you need someone to turn to.
She's your default shoulder to cry on.
7. She won't say no to you -- not even to the craziest requests.
And you've certainly requested your fair share of craziness.
8. She'll wake you up for midnight margaritas!
9. She's always there to listen.
No matter how tired she is.
10. You spent half your childhood together up the biggest tree in the yard!
And it was always a race to see who could get higher.
11. She's happy when you're happy.
It's a weird sister thing -- you share emotions, no biggie.
12. You never get tired of matching Halloween costumes!
Even though they're usually the same every year...
13. You'll always stick together no matter what!
Tell us why your sister is your best friend in the comments below!
And don't forget to join us for 13 Nights of Halloween on October 19, only on Freeform.