Twincest 

Twins in which engage in sexual intercourse, or fullfill each others sexual desires.

Some famous examples are:
The olsen twins are twincest
the Harvey Brothers practise twincest

Twincest by Dylaoptupus February 5, 2010

twincest 

A suitable subject for Harry Potter slash fiction about a certain pair of Weasley brothers.

Fred/George = TWINCEST!!!

twincest by Alianne September 14, 2003

twincest 

twins having sex.. its so wrong, yet it feels so right

me and my twin have twincest. i fuck my twin, and enjoy it.

twincest by nadia_aidian February 28, 2004

twincest 

When twins go at it in the sack and it is hotter than anything else.Taboo twins carries hotstories about twins original and fan fiction.

The hot twincest stories found here tabootwins.com

twincest by taboo twins June 1, 2010

Twincest 

Twins preforming incest

Jerry and Jessica loved each other so much, they preformed twincest

Twincest by death by a spoon January 26, 2010

twincest 

Something Good Charlotte, Fred and George and Mary-Kate and Ashley fans dream about.

Me:twincest...insn't that wrong?
GC fan: Only if u swallow, liek!!111

twincest by Michelle The Pirate July 11, 2004

Twincest 

Incest between twins

“I enjoy twincest porn.”
“My little brother and sister engage in twincest and I like to watch through the keyhole while I bop the ole’ chode.”
“Jaimie and Cersei Lanister on Game of Thrones have a twincestuous relationship.”
“Twincest is wincest.”

Twincest by Resicoi July 6, 2019