A bitch you can stick your fist inside of her pussy, no lube necessary. The word sister referring to any random female.
The girl i met last night i was down to fuck, until i realized it was Sister Fister.
by brando239 November 18, 2008
Top Definition
The act of fisting your sister. Commonly refered to as incest.
Yo this kid named Francis is a fucking sister fister.
by Quay and Justin October 29, 2003
a brother or even a sister that likes to casualy fist their sister up the vagina or even the arse hole. Most of the time resulting in a very sore vagina/anus, and if caught resulting in a sentence of 10 years in jouvey.
(here is a role-play of a sister fister and his sister)
Kirsten after a long sleep
Kirsten: o hi there Aaron i didnt see you over there in that dark corner.
Aaron: You dont need to see me, you just need to feel me
Aaron and Kirsten both grin and Kirsten turns around
by mitch aka titch June 11, 2006
Anyone who has shoved their hand into a friend's sister's cunt
2) I pulled the sister fister on blakes sister
by Zane April 04, 2003
Strictly, one who indulges in a particular form of incest, using only their hand (see fister. Often used as a term of contempt, and shortened to "sissy" on account of their unadventurousness.

See also brotherfucker.
Your brother's such a sisterfister, you know.
by Lucifer B August 16, 2005
The act of fisting your sister. Commonly refered to as incest.
Yo this kid named Nicholas O. is a fucking sister fister!!
by Dankolas O. January 25, 2016
A person who fists peoples sister
amr fisted my dog
by me March 01, 2004
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