From the back of the box:
Pick a shape card and lay it down. Add another! Then another! Take turns adding new shapes until . . . You've made a Silly Body."
The rules give four different games that you can play with the shape cards: We Made It Together - a cooperative variant in which the players take turns laying down cards until they both think they've made a silly body; On Our Own - a competitive variant where each players takes 20 or 30 cards and makes as many silly bodies as he or she can; Use 'Em All Up - a competitive variant where each player takes 20 or 30 cards and uses them all to create one incredible silly body; and Jump and Switch where after completing one of competitive variants you switch cards with your opponent and play the game again.
The shape cards have many different shapes and colors, but are made out of very flimsy cardboard.