A shot of vodka that is swept in the mouth from side to side and then either spat out or (usually) swallowed in the absense of toothpaste or mouthwash, or from excessive lazyness
Since I lost my toothbrush in the woods on the camping trip, I had to pull a russian mouthwash two nights in a row.
Another term for "curb stomp", the act of forcing someone (usually unconcious, sometimes not) to bite down on a street curb, usually at the corner, then stomping on the back of their head. This can cause broken teeth, sometimes forcing the teeth into the skull which can cause brain damage, a broken neck, lips splitting at the seams (hence another slang term for curb stomping, "smiley" or "Kingswood Smiley"), and, depending on the force of the stomper, seperation of the head across the hemisphere.
In American History X, Derek Vinyard gives a young African American a Russian Mouthwash for trying to steal his car.