Shannon Twins: Karissa Will Drive ... Because Kristina Charged with DUI

Former Playboy Playmate Kristina Shannon just got a new role ... DUI defendant.

Kristina and former fellow Playboy Playmate/twin sister Karissa were injured when Kristina smashed their Benz SUV. They were en route to get their nipples pierced.

It's Kristina's first DUI, so she'll probably get off with probation.

Both girls like to party together, and drinking is part of the drill.