I use to play this with my brother and sisters sometimes. What you do is sit in some kind of circle, and you go around the room. The first person describes the first feature. It can be any feature they choose. Maybe they'll say long, thin, dreamy eyes. Then everybody will draw that feature however they interpret it. Then it's the next person's turn to describe a feature. You go around the circle thusly, until someone decides that the character is complete. Then, everybody shows everybody their drawings. You can't let anyone see it till the end.
I played this game with Sam Gorrie at a coffee shop when she was in town. Here are the two people I invented. The first turned out to be a weird looking, whistling, break dancing girl. The second, a smelly, star-struck girl. I included the bottom portion of the first sketchbook page because it's a drawing of Patrick that turned out fairly well, and also there's some type doodling.