"Think about a place, an object, a character... From a book you like. 
Draw it on my back, while you're drawing,
I'll try to draw as well what i'm feeling"

One image. What sign will each of us extract from it ?
Storytelling

The first who invades the other's space wins

One person = one pattern.
20 seconds to draw.
Switch

Interpretation
One door, two rooms.
One is knocking, the other one has to guess the knocking's location

Hands experiments
Disorientation

20 seconds right hand-20 seconds left hand

right hand-eyes closed

left hand-eyes closed

both hands-same time

both hands-eyes closed-same time