A rubber ball contains saturated sand, and water reaching into the neck of the glass tube inserted into the ball, above the sand. When squeezing the ball between two fingers, the water level appears to go down. This phenomenon, which is often used in geotechnical laboratories to demonstrate the special properties of soils, can be explained by assuming that the initial density of the sand is very high (if this not the case the sand may be densified before the demonstration by knocking the ball several times onto the table, preferably before the arrival of the spectators). The squeezing of the sand results in a shear deformation, and in this dilatant material this is accompanied by a volume expansion of the assembly of granular particles. This means that the pore volume increases, and thus water is drawn into the ball from the glass tube.