A joust is a play you want to try to avoid in beach volleyball. A joust occurs when the ball is on the net in a 50-50 position and both players contact the ball at the same time.
It's similar to a jump ball in basketball but instead of getting the ball kind of tossed up, the ref has to make a call of who contacted the ball last and then that other team gets the point.
So the joust, both players go at the same time. One's pushing, the other one's pushing. The ball goes one way or the other.
The last one to touch is usually the first one to touch and it pushed the ball out of bounds. So that team that pushes the ball out of bounds loses the point. You want to try and avoid a joust situation by setting your partner off the net between two and four feet.
If you set your partner over the net, or within the one-foot line to the net, then a joust situation has a higher probability of occurring.
Since referees don't always have the best judgment, they just do what they see. And what they see may not have been what actually happened. You're putting a referee in a situation to determine a point in a game.
The biggest part of beach volleyball, in my opinion, is taking the referee out of the game and avoiding a joust situation all together.