A word used to describe a pairing/threesome between a combination of the characters commonly referred to as the "Sand siblings" in the manga/anime series Naruto. There are three sand siblings, Temari, Kankurou and Gaara.
I was reading a really great sandcest fanfic yesterday- they paired Kankurou and Gaara.
Have you seen that Temari/Kankurou/Gaara picture? That's some hot sandcest!