Question: What do volleyball players do to hide block signals from the opposing team?
About the article "Beach volleyball", section "Block signals".

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Beach volleyball players use hand signals to indicate the type of block they intend to make.
Block signals are made behind the back to hide them from the opposing team.
They are usually given with both hands by the serving player's partner prior to the serve, with each hand referring to the type of block that should be put up against an attack from the corresponding opponent.
A player may also "wiggle" or "flash" one block signal to indicate which opponent to serve to.
If the server is the designated blocker, he or she may run up to the net to block after serving.
Otherwise, the signaling player will perform the block.
Block signals may also be given during a rally while the opposing team is preparing their attack.
In Mus, passing gesture signs indicating which cards you have to your team mate is perfectly legal, being a decisive strategic factor.
However, these signals can only be the ones specified in the rules as explained below, any non-standard signal is not allowed and would result in disqualification if proved.
Knowing your partner's cards and letting him know yours results in a more effective play and allows a more accurate evaluation of the team's chances to win each bet, however if the rival players see you or your partner while passing a signal, and gets to know your or his cards, your chances will be seriously compromised.
If you detect a rival's signal and the rival doesn't realize you know his play (that should require not to inform your partner about the signal you blew up, if he didn't see it) you'll become able to find a weak spot in his cards to counter-attack reversing the hunter-prey role or at least avoid his strong-point beads.
There are many commonly accepted signals ("keinuak") allowed in the game.
You can use any of them to indicate to your team mate the hand you are holding (while trying to hide the transmission of the signal from your opponents).
The signals have a fixed meaning and it is against the rules to use other signals or use false signals (by signalling a hand you do not hold).
The "keinuak" are: *Two Kings: biting the centre of the bottom lip *Three Kings: biting one side of the bottom lip *Two Aces: poking out the tongue *Three Aces: poking out the tongue to one side *Single Pair (pares): tilting the head to one side *Three-of-a-kind (Medias): pursing lips to one side of the mouth *Two-pairs (Duples): raising the eyebrows *31 (La una, i.e.
31-point Juego): winking *30 (30 puntos): lifting both shoulders *29: (29 puntos): lifting the right shoulder *28: (28 puntos): lifting the left shoulder *I have nothing (Ciego, blind).
This indicates a bad hand: closing the eyes *Royal 31 (31 real, see above): touching the earlobe Not all of these signals are accepted in all variations and there might be other signals in use.
It is always good to clarify the signals in use when playing for the first time.
Players have a wide variety of approaches to signal use, some players make a great number of signals, as soon as they have the chance, some players seldom or never make signals.
On the other hand, some players show a honed skill in catching the rival's signals whereas other players do not even make too much an effort to disrupt the opposing couple's signals; some would stare continuously and overtly to the rivals' faces for intercepting signals and others would pretend to get distracted or to be not too interested in catching rival's signals in order to make them overconfident and thus catch subsequent signals. 
There are a number of ways in which 9-man rules differ from traditional Volleyball rules.
As only men can play 9-man, during international tournaments, such as the NACIVT, women play by six-player Volleyball rules.
Rotating: Players in 9-man do not rotate as in traditional volleyball.
As such, players tend to specialize in two or three positions.
Serving: Any of the three players in the back row can serve at any time.
The players may serve from any position behind the line.
Jump serves are not allow as one foot must remain on the ground while serving.
Scoring: 9-man implements a rally scoring system.
Teams do not have to be serving in order to win a point.
The first team to 21 points while holding a lead of at least two points is the winner.
If there is no two-point lead, the first team to 25 points wins.
Touch Limit: Each team is allowed three touches before the ball must be sent over the net to the opposing team.
A block counts as a touch.
A team is awarded an additional touch if the ball contacts the net during a volley.
The other team is awarded a point if the ball comes into contact with any body part besides the arms and hands.
Blocking: You can not penetrate across the plane of the net (called "piking").
Blocks must be straight up.
If the ball comes into contact with your head, the play goes to the other team.
Ball Handling: There are several specialized moves in traditional nine-man.
The preferred method of passing the ball is called a chai ball—an underhand scooping move.
The fai-gok or fastball is typically the centermost position in the offense that has a signature move resembling a basketball dunk.
The player pushes the ball upward and then quickly changes the direction of the ball slamming it to the ground.
A net ball (pushing the ball into the net so that it rebounds and you can play it again) is often performed by the setter to upset the timing and rhythm of the game and throw off the defense.NACIVT Rules: NACIVT rules stipulate that at any given time, each team must have at least six players of "100 percent" Chinese descent on the court.
The remaining three players must be of Asian descent. 
Also known as 'ghost volleyball', it is another variation that tries to remove height of players as a determining factor in team success is blind volleyball.
Ad-hoc blind volleyball is where sheets are draped over the net so one side cannot see the other side.
A more formal type of blind volleyball removes the traditional volleyball net and replaces it with a tarp thick enough that shadows cast on it cannot be seen from the other side.
Blocks are almost impossible to do since it is difficult to know where the ball is going to come over the net.
Spikes and overhand serves are prohibited because it is already very difficult for the receiving team to react to any incoming ball without the increased speed of a ball struck in such a manner.
Blind volleyball additionally creates a higher level of suspense for spectators, who, unlike the players, can see what is taking place on both sides.
Another unique feature of blind volleyball is how it can make the back row the row that hits the ball over the net.
In regular volleyball, the back row tends to receive the volleyball and then move it to the front row.
In blind volleyball, moving the ball to the back row makes it harder for the other team to see where the ball is and by hitting the ball on a flatter trajectory, the back-row players can more easily surprise the receiving team on where the ball will be coming over the net. 
Traditional volleyball has its roots in East Africa, India, and Pakistan.
The game is usually played within the Ithna Ashari Muslim, Bohra Muslim, Ismaili Muslim, Punjabi, and Hindu communities worldwide.
Traditional volleyball varies from indoor gymnasium play, outdoor play on sand, grass, or clay, as well as street volleyball for recreation.
There is a 3 touch system like International volleyball, however, traditional volleyball does not require the bump-set-spike scenario.
Instead, traditional volleyball is based on a consistent volley of the ball, only the serving side can score, and players play a style which is considered "closed hand/fist" play.
The game can be played with up to 9 participants per side (similar to Asian 9 man volleyball, but with variations to the game), or as little as 5.
There is no rotation in traditional volleyball, however, in certain East Indian and Southeast Asian communities, they do allow rotating as the rules tend to vary from team to team.
The court can vary from 30' to 30' to as large as '35 by '35.
Some of the best traditional volleyball teams are centered in Canada, from Toronto North, Toronto East, Jaffery's and United Stars, to Calgary, Edmonton, Vancouver, and Port Moody.
The weight of the ball varies as well, in North America they play with a lighter ball, around 10.5-11 lbs.
of pressure.
However in East Africa, India, and Pakistan the game is played with a heavier ball, anywhere from 12 to 14 lbs.
of pressure.
Spiking is usually allowed on first contacts with the ball, however this is no longer allowed in North America.
Some of the key positions on the team are Net Center (or nettie), he is responsible for lifting and/or digging the ball out of the net on a second touch.
In the old days, the nettie was encouraged to lift the ball up and over the net to the opposing team.
As the years went by, and the variant styles of the game were changing, the nettie was encouraged to lift the ball back to his team so that they could strike the ball (third touch) to the opposing side, and keep the volley going.
There was usually 1 nettie per team, today, teams are allowed to play with up to 2 netties simultaneously, or even a third nettie on the far right or left corners of the net-thus preventing an advantage of the opposing team to drop or 'dink' the ball.
The short center position, which is relatively new, is a position that was previously called the 'sweeper' position.
This position was put into fruition in Canada some years ago, and the object of the short center is to strike the ball into the net as much as he can, so that the nettie can give a nice, high, clean lift to his team to strike back to the opposing side.
The third and probably most important position is the Long Center (formerly third line), he controls the pace, tempo, and speed of the game, and is instrumental in taking points by a method called flights or shooting.
Everyone else on the team, from the front line wings to the back line wings, as well as the serviceman also play pivotal roles on the team.
The serviceman is not allowed to serve overhand though.
Traditional Volleyball teams play in local, state, provincial, regional, national, and even international tournaments every year.
From Dar es Salaam and Nairobi, to Karachi and centers in Western Europe, the game is growing, more youth are now playing traditional volleyball, and the hope is that one day, this version of volleyball could be played at the Asian Games or even the Olympics.
Unlike the FIVB, there is no governing body for traditional volleyball.
There was an attempt in the mid to late 1990s and into the millennium, to form a North American league called TVANA-Traditional Volleyball Association of North America.
This league had three tournaments in Houston, before folding.