double-sister-in-law 

Brother’s wife and spouse’s sister at the same time.

My double-sister-in-law is a good person.

double-sister-in-law by Rwopazaq November 24, 2019

Ugly sister 

has a butt for a face.

I have an ugly sister, called Amber.

Ugly sister by wampummmmmm May 26, 2020

Your sister's cleavage 

That thing you try to not look at but a part of you can't look away.

You think you're the only one haunted late at night by your sister's cleavage?

Your sister's cleavage by ApricotFields June 29, 2020

Grandma Sister

The most disgusting thing people in Alabama can do, when your grandma is also your sister

man i got with grandma sister the other day, i love her old pussy

Grandma Sister by alabamainsest August 2, 2020

Bag Sister 

One that is all about her money and growth while uplifting others to see their full potential.

I just told my bag sister about this upcoming business venture.

Bag Sister by J.Shanelle November 8, 2020

saddle sister

When you and another person has had sex with the same man.

Me: Hey guess who I took home yesterday? I have a new Saddle sister.I rode that Dick for hours last night.
Friend : please tell me its not my ex ? I don't need you for my saddle sister he add to my family he s been around so much its like we should have reunion.

saddle sister by Stay slow January 12, 2021

Hillbilly sister sticker 

Foreplay act ; see Kentucky plug for full definition

“Hey paw, you should see what marybeth and me invented, we call it the hillbilly sister sticker”

Hillbilly sister sticker by Tainted Sasquatch May 20, 2021