A girl that is always showing off some part of her body unintentionally, thus giving every guy around her a free show. Typically refers to a hot girl with large breasts and ass to show. If the girl is a frequent freeshow, her name can be unofficially changed to freeshow, letting you comment about her freely without her realizing.
Hey, look over there... it's a freeshow!
Have you seen freeshow today? She's hanging out even more than normal!