Hacky sack
A footbag is a small, round bag usually filled with plastic pellets or sand, which is kicked into the air as part of a competitive game or as a display of dexterity. "Hacky Sack" is the name of a brand of footbag popular in the 1970s (currently owned by Wham-O), which has since become a generic trademark. The most common game of footbag consists of two or more players standing in a circle and trying to keep the sack off the ground for as long as possible. History. Footbag-like activities have existed for many years. The  game is similar to traditional Asian games of kicking the shuttlecock, known as "jianzi" or "chapteh". The game is also similar to some South East Asian games, such as "sepak takraw" and "sipa". This game is known as "jegichagi" (제기차기) in Korea. The Wu Style Tai Chi Chuan practice dates back to at least the 1930s, and French policemen are seen playing a shuttlecock game in the 1955 American film "To Catch a Thief". The same principle is applied in football-playing countries in activities of freestyle football and keepie uppie. The current Western incarnation of the sport was invented  in 1972 by Mike Marshall and John Stalberger of Oregon City, Oregon, US with their "Hacky Sack" product, the rights to which are now owned by Wham-O. Although Marshall suffered a blood clot and fatal heart attack in 1975, Stalberger continued the business. It gained national popularity in the early 1980s, and Stalberger sold the title to Wham-O in 1983. Equipment. For circle kicking, it is very common to use a crocheted footbag, which is usually filled with plastic beads. Casually, footbags are often differentiated as normal (indicating a plastic-pellet filling), or as "dirt bags" or "sand  hacks" (indicating a sand filling). In the freestyle footbag discipline, a 32-panel bag is the generally accepted standard (the number of panels on commercially available bags can range from 2 to 120 panels). Stitchers generally use Plastic Poly Pellets, sand, BB's, steel shot, lead shot, seed bead, or tungsten shot as filler. Most professional stitchers use a custom combination of different fillers to make the bag play better. Bags usually weigh between 40 and 65 grams, depending on the type of filler and amount of filler used. 32-panel bags do not stall as easily as a "dirt  bag" or "sand hack", but set truer from the foot, allowing for more complex tricks. Professional footbags are usually made out of the fabrics ultrasuede light, facile, or (a sub-brand of Clarino artificial leather). While these bags can last a long time with proper care, they are quite fragile relative to their more common crocheted cousins. The footbag net discipline uses a distinct bag, characterized by a harder outer surface than other footbags. These bags are not suitable for freestyle, and vice versa. There are also several novelty products available, including glow in the dark, chain mail, and even  flame retardant bags that can be set on fire and played with. The fire footbag has been banned in South Australia. Shoes. Most advanced freestylers wear various styles and brands of tennis shoes, the most popular being the Adidas Rod Laver tennis shoe. Several shoe modifications are common in freestyle footbag. In order to make toe stalling easier, many players use special lacing patterns that pull apart the sides of the shoe near the toe area, creating a broad, rimmed platform. Modified lacing is augmented by cutting away the stitching that joins the row of eyelets to the toe. The  area that is created by completing these modifications is called a toe box. Shoes can be further modified for freestyle footbag by removing layers of fabric from the inside, outside, and toe surfaces. These modifications are advantageous because they allow players to more accurately feel the bag on their foot. Games. Circle kicking. Circle kicking is the most common game played with a footbag, and is often what people mean when they use the term "hacky sack". Players stand in a circle and keep the bag moving around the circle, with the goal of keeping the bag from touching the  ground. There are a variety of terms used by different groups of players to note when the footbag has been touched by every member of the circle. The game starts when one player picks up the sack and tosses it to the chest of another player, who allows it to fall to their feet so they can kick it, and play begins. Play continues until the sack falls to the ground, then a player picks up the sack and the game resumes. The object of the game is to keep the sack off the ground for as long as possible . If every player gets a touch to the sack before it hits the ground, it is called a 'hack'. If every player gets two touches before the sack hits the ground, it is called a 'double-hack' and so on and so forth. Circle kick is generally accompanied by an unwritten set of etiquette guidelines designed to keep the game fun, friendly, and open to everyone including new players. The most basic rule is to respect all other players. Some other general guidelines include picking up the footbag after you drop it or kick it away, rather than having someone  else retrieve it; not serving the footbag to yourself; not spitting in the circle; and not hogging the footbag (often called jestering, or the player may be called a hack-hog) and making sure to pass the bag to players who have not gotten it recently. Most circles are very open to new players and will not ostracize anyone for being less coordinated or well practiced than the rest. Some circles have an unwritten rule that there is no apologizing when a person drops the footbag. This guideline is designed to keep the new players from feeling as if it  is their fault that the game is slow, and it keeps the experienced players from having to constantly reassure the new players that it is not their fault. Freestyle footbag. Freestyle footbag is a sport in which the object is to perform tricks with the bag. The ending position of the footbag on one trick becomes the starting position of the footbag on the next trick. Tricks are created by combining different components between contacts with the bag (contacts can be either stalls or kicks, though stalls are more frequent). Components include spins, dexterities (using a leg to circle or  cross the footbag's path in mid-air), jumps, and ducks (letting the footbag pass a few inches above the neck). Contacts are usually on the inside of the foot behind the opposite support leg (Clipper Stall) or on the toe, however, many inventive possibilities remain and are used to create an endless list of tricks. A partial list of freestyle footbag tricks can be found at the official Footbag WorldWide Information Service. Various styles have developed as the sport has become more popular. Players can choreograph routines to music, alone or in pairs, executing difficult moves in sync with  the music—the result is something like a cross between rhythmic gymnastics and figure skating. There is an annual footbag world championships held each year. The current freestyle world champion in singles category is Jan Weber, of Czech Republic. Footbag net. In footbag net, players (either playing individually or with a partner) volley a footbag back and forth over a five-foot-high net. This game combines elements of tennis, badminton, and volleyball. The court dimensions and layout are similar to those of badminton; the scoring is similar to the old scoring system in volleyball (a player must be serving  to score); and serves must be diagonal, as in tennis. Footbag net games can be played to 11 or 15 points, although the winners must win by at least two points. Rallies in footbag net look a lot like volleyball (e.g., bump, set, and spike), with players spiking from an inverted position in mid-air (over the net) and opponents often digging very fast spikes into bumps or sets. Play in footbag net is very similar to Sepak Takraw. However, in footbag net, it is an "upper-body foul" if the footbag touches any part of a player's body  above the shin. Hacky attack. Hacky Attack is a particular "footbag" discipline, played by two teams made up of two players each. It is practiced on a field, generally of sand, formed by a rectangle of 10 x 15 meters. One of the two players, the "pitcher", tries to hit the opposing pitcher with the ball ("footbag"), who instead tries to avoid being hit. The other player, the "catcher", has instead the task of picking up the ball and passing it to his thrower. When a pitcher is hit, he switches positions with his teammate. The first team to reach  15 points (the point is scored each time the opposing pitcher is hit) wins the game. Hit the man. This particular discipline, practiced mainly in Northern Italy, was founded in 2009 by some university students and consists in hitting the opponent with precise and spectacular shots, on the street or in public places. In this game, footbag is commonly called Street Ball, due to its ability to play in the crowd.