Top definition
When someone is sexually intimate, or develops an incestuous relationship, with his or her own twin.
1. "The McPoyles from 'It's Always Sunny in Philadelphia' are definitely guilty of twincest."
2. Person A: "Dude, did you see those two guys going at it? They looked exactly alike!"
Person B: "Yeah, man, didn't you know? They're in a twincestuous relationship."
2. Person A: "Dude, did you see those two guys going at it? They looked exactly alike!"
Person B: "Yeah, man, didn't you know? They're in a twincestuous relationship."
by NecroManzie September 27, 2009
4
TWINCEST example: Hikaru Hitachiin and Kaoru Hitachiin
(if you dont know who they are, LOOK THEM UP)
(if you dont know who they are, LOOK THEM UP)
by ASIAN >.< Wu-Dawgg May 07, 2010
5
Incest between any set of multiple birth siblings. Twincest can occur between twins, triplets, octuplets, etc. Twincest may also occur across gender lines (sisters, brothers, or both). Twincest can be any level of sexual intimacy.
by T-Winner July 10, 2009