A small cloth bag filled with beans or other small objects, for the most part used in children's games. Bean bags are easier for smaller children to catch and grasp than a ball, and have enough mass to be thrown with effective results (knocking stuff down!), but at the same time, are soft enough that they don't cause much damage if they hit someone.

Another advantage to beanbags is that children can make them themselves (with adult supervision). Get two square pieces of cloth (or one rectangular one, folded over), sew up three (two) edges to make a bag with an open top, fill with dried beans, and sew up the remaining side. If your kid is old enough to safely use a needle, this is a good way to keep them busy for an hour or so. (Or might teach them to use a sewing machine).

You can also make beanbags in fun shapes -- circles, triangles, stars, animals, you name it. Beanie Babies were a take-off on this idea.

Sometimes beanbag is used to as shorthand for Beanbag chairs -- these are really big bags (made of leather or something meant to look like leather, in most cases) filled with small plastic or foam pieces.

Sometimes written as bean bag.

Also a slang word for the scrotum and testicles.

Example:
I told her I liked the way her pink thong showed through her hip-hugging, white pants and she turned around and kicked me in the beanbag.

A bean bag is a small pouch of flexible fabric or plastic containing styrofoam, plastic, or actual beans. Small bean bags are frequently used in throwing games at carnivals and other outdoor events, while large bean bags, in the form of bean bag chairs, can be used as a comfortable seating arrangement.

Due to the property of conforming to the shape of an underlying surface that bean bags have, they are often used as a backing for things that require stability on an uneven surface, such as lap desks.