A fluffer is someone on a pornographic film set that keeps a male performer's penis erect in between scenes.
In the 1950s, a fluffer began referring to a person who kept male performer’s fluffed up, or erect, during a shoot. It makes sense, given shoots can go on for hours at a time. These very important people on set could be male or female, and are usually clothed. A fluffer is also usually only for men (sorry ladies).