I smile because you're my sister. I laugh because there's nothing you can do about it.
Being a sister is like being born with a built-in best friend.
When life gives you a sister, you never run out of stories to tell.
No matter how much we fight, my sister is still my favorite person to annoy.
Life was boring until my sister showed up to spice things up.
Having a sister means you always have a partner in crime.