We have a Spongebob+Patrick relationship :)

Oh, yeah, man.
My sister and I are best friends. The great thing about this is that we're twins. Only seven minutes apart, and she tells me those were the best seven minutes of her life.
We're irreplaceable, it's quite obvious.
We insult each other and slap each other on the arms or head, we make fun of each other and then turn to insult someone else.
We speak at the same time, or say exactly what the other was thinking. We tell the other of her genius, and we laugh about the insults we throw around at each other. We watch movies side-by-side, and if we go out, we link arms. We talk about the books we adore, the characters in the stories we write. I call her a lunatic and she calls me a maniac.
My twin sister is, quite frankly, my most beautiful, most marvelous soul mate. After all, what else is a soul mate but your very own heart?
And she is certainly that.