Twincest 

When twins are in a romantic or sexual relationship with each other.

TWINcest is WINcest

The Hitachiin twins. Look it up.

Twincest by The sexless knight June 27, 2017

Twincest 

The de facto title of a series of Coors commercials from the early 2000's.

My buddies and I are really into identical twins, so a few times a week we throw some Twincest on my TiVo, crack open a Coors, and fill up 4 jumbo breast-sized water balloons a piece to smoosh in our collective faces.

Twincest by The Booz June 30, 2011

Twincest 

Something that is so wrong in real life but so right in anime.
Giving a whole new meaning to "go fuck yourself".

If you ask me, the sexiest twincest is Hitachiincest (Hikaru x Kaoru Hitachiin) from Ouran Highschool Host Club. But my friend hates it. But then again she hates yaoi sooooooooo...

Twincest by 730cute September 17, 2014

twincest 

To date, "hook up" or flirt with someone who closely resembles a friend to avoid messing up the friendship.

Girl 1: Dude, that kid totally looked like your best guyfriend!

Girl 2: I know! I had twincest with him.

twincest by RainbowRider January 1, 2011

Twincest 

A word pertaining to the pairing of Fred and George Weasley, twin boys from the Harry Potter Series.

I absolutely love Twincest, even though James Phelps suggests it's wrong

Twincest by PunkxxRoyale December 28, 2009

Twincest 

When two twins both female do anything sexual to either each other or to someone else with each other.

The twins both screamed at the word twincest.

Twincest by PainCorp July 11, 2004

Twincest 

When twins get together in a odd and disturbingly immoral relationship to the out side world. A mix of incest and twins.

Laurie: damn you see those blonde twins over there, they are having a twincestual relationship
Josh: that is gross, and not to mention immorally disturbing.
Laurie: damn straight it is,andi thought the girl was hot.
Josh: obviously so did her brother.
Laurie: just like those gay scots the proclaimers.
Josh: lool

Twincest by Chizeej- on behalf of Lozz April 25, 2007