look up any word, like dirty sanchez:
 
3.
what you say when a girl ditches her girlfriends to chill with her boyfriend
if a girl blows off her friends, or just hangs out with her boy instead of her girlies, and they're offended cuz they know they love her more.

similiar to guys's bro's before hoe's
Kate: oh sorry Ali i cant go get a mani-pedi with u and sylvia, im going to the movies with ben
Ali: aww, come on kate! sisters before mister's!!

Ali: hey kate come over to our table!! we got wings...
Kate;: hahaha no sorry, Ben already ordered wings too..
Ali: ugh, sisters before mister's!
by I. M. Cold February 22, 2010
 
1.
The unwritten law that dictates that a the wishes of an unmarried woman's or girl's female friends trump those of a men she wants to have a relationship with. This law exists to protect said woman from being roosterpecked or whipped and her boyfriend's a pig or a man slut.
Better known as ladies first and to hell with your boyfriend.
Yo, lady, don't let that male chauvanist pig tell you what to do. He thinks you're just another piece of ass. After all, it's sisters before misters.
by Stop the Pendulum March 06, 2006
 
2.
The girl rule that your friends are always more important than your boyfriends. Basically the girl version of bros before hoes, except the title doesn't sound like an insult to women. Also, there's an unwritten sub-rule: if you catch your friend's boyfriend cheating, YOU MUST TELL HER ASAP!

Sometimes called chicks before dicks.
Amy's boyfriend was being such a jerk to her BFF, so she dumped him, even though she still really liked him. What an awesome friend Amy is, putting sisters before misters like that!
by Disvan November 24, 2010