The goal with the exercise is to train the players to make a precise pass and teach the receiving player not to slow down when receiving the ball.

 The "clay pigeons" runs straight forward with the body turned against the passing player.
The passing player must now shoot after the chest on the running player, who has both hands up, ready for catching.
The pass and the running is a success if the runner - without altering the speed of running, without jumping or bending and without reaching forward or backward - is able to catch the ball.
An non-precise pass could cause the passing player to make a couple of push-ups or something else.
In the same way the running player could be punished with push-ups if he/she alters the running speed.