Give each person a piece of paper and a pencil. Have each person place their pencil on the paper and on the count of three everyone begins to draw one continuous squiggly line all over the page. Say "stop". The squiggle should only take two or three seconds. Now everyone pass their squiggle to the left. Now have each person look at their drawing for something familiar and for the next 10 minutes create that item in detail.
Let's say I have a squiggle that I think looks like a dragon, so I add eyes, teeth, wings, and claws, using the already formed neck, head, and body of the squiggle. Its okay if other lines don't quite go with the picture, it's creative. When time's up have everyone share their picture with the group.