Big Sister Milk 

Fresh arousing milk produced from the finest 2D onee-chan's oppai

My onee-chan gave me a sip of her big sister milk!

Big Sister Milk by Your Secret Urges August 12, 2018

Divine Sister 

A popular LGBTQIA+ community that exhibits cultic behaviors and has been through multiple famous controversies throughout the popular virtual platform Roblox, over the ages.

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This community is currently home to two popular survival games with a unique plot and lore behind each one

Les Beyond East - LBE

De Pride Isle Sanatorium - DPI
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You: "I really enjoy interacting with the holy community that is Divine Sister, It's such a holy experience!"

Divine Sister by O0O0O0 June 24, 2021

Penny War Sister 

A member of the female race who has problems with the actions of members of the male race and certain members of the female race but only makes these comments heard amongst a forbidden section known as the 'sisters section' and their cliques

The penny war sister just personally attacked me on the board because she was too scared to say anything to my face

Penny War Sister by The voices made me do it November 8, 2008

Nepgear [Purple Sister] 

That one chick from Discord who pretends is a character from Hyperdimension Neptunia, and all her discord messages are censored, because that's just life, don't ask me.

It's worse to be called Nepgear Purple Sister than it is to be called Mama Kat.

Nepgear [Purple Sister] by Yoursisteristrans June 29, 2018

mister-sister 

Someone of the male species, that wants and or appears to look like a female.A male that is very feminine, also known as a "shemale"

That gay guy looks like mister sister

mister-sister by Nicki November 10, 2003

babylon sister 

a party girl, a girl who indulges, a fiend, a girl who gets down, a chick you can fuck, and you dont want to run off after your done.

man she loves the cocaine, babylon sister shake it!
a female steely dan fan
a really cool chick who likes
to party

babylon sister by frankenfoot April 28, 2007

your sister looks like a wookie

Like it sounds. Also the name of a song by the band called Analy Inserted Angle Grinders from Dominic College in Tasmania, Australia.

OMFG YOUR SISTER LOOKS LIKE A WOOKIE(Insert chewbacca noise here).

your sister looks like a wookie by Some guy from Dominic College. September 29, 2008