A Happy Sack is a sentient rubber bodybag. It sells in packs of 12 and is recyclable.
The Happy Sack is designed with three flaps, one which has the imprint of a face on it. As the sack moves up the body, it will latch onto the arms and pin them over the breasts and crotch. The sack will then start to seal two of its flaps at the shoulders, and then the masked flap would pull over the head before snapping over the face.
The mask is mainly designed to grab the mouth and force it into a big smile. The rest of the sack is designed to move the fingers and make them rub certain body parts. This of course will stimulate the wearer, and over time, the sack will allow the wearer to continue pleasing themselves on their own. The sack remains tight but allows some movement for the wearer to move their hands up or down.
The Happy Sack pauses at random intervals to check for the release switch: a smile. However, the smile had to be authentic, and by authentic, the smile is the result of mind-blowing masturbation. If this smile works, the sack does release itself. The failure to smile or to escape the sack at that time, however, will reseal the Happy Sack and repeat its functions.
By default, a Happy Sack is clear, though it can come in various shades. A Happy Sack can also be sold in opaque colors. Accessories for Happy Sacks can allow the sack to preserve the shape of the hair and can include collars or Senshi frills.
Some people have taken to design their own Happy Sacks, adding on cat-like or maid features. Some sacks were also designed to fold and spread the legs apart while others are capable of merging with other Happy Sacks. Another Happy Sack was designed after a woman even though its occupant was a male.
Those who visited the Chainsman Institute may recall two experiments.
The first experiment is Surgi-Tape. This is a clear yellow wrap that adheres to itself and create a seamless wrap. It's molecular structure does have a habit of shredding clothes, however. Surgi-Tape becomes rigid after too much movement is applied, but at the Institute, escape is not a practice.
The second experiment is Molding Tape. Unlike Surgi-Tape, Molding Tape solidifies upon contact with a surface. The surface can then be grabbed and moved, and it will retain that shape even when released.
Testers were first wrapped up in Surgi-Tape from head to toe, and then Molding Tape was applied over their faces. The person in charge of this experiment decided to have fun and adjust the faces so that they would remain with a wide-eyed smile. While the combined experiment do resemble the Happy Sack, sexual activities are forbidden at the Institute.