Lawn tagging. Static electricity caused by vigorous rubbing will bring the black rubber sand-beads to the surface on an artificial turf.
IEC 60065 Edition 8.0 2014-06: Audio, video and similar electronic apparatus (Artificial Turf is a Van de Graaff Generator) – INTERNATIONAL STANDARD
220.127.116.11 Determination of HAZARDOUS LIVE parts
d) the energy of discharge exceeds 350 mJ for stored charges at voltages exceeding
15 kV (15,000 Volts) d.c. page 54
Multiple rubbing of player’s skin across artificial turf (think goalie diving) can exceed 350 mJ of energy transferred @ 15,000 V (IEC 60065). Atmosphere and Earth (ground) will try to bring human back to neutral by donating electrons and negatively charged ions to make up for electrons that were lost to turf.