Abstract: A paintball grenade that disperses a marking fluid upon impact. In one embodiment, the paintball grenade includes a flexible, resilient tube sealed at both ends. The tube includes a distended portion containing pressurized marking fluid and a side discharge port for discharging the marking fluid along a discharge axis that is approximately transverse to a longitudinal axis of the tube. A blocking member is disposed in the tube that is movable between a closed position that prevents fluid communication between the distended portion of the tube and the discharge port and an open position that allows fluid communication between the marking fluid and the discharge port. When the paintball grenade is thrown and impacts an object, this results in hydrostatic shock through the marking fluid, which moves the blocking member from the closed position to the open position, thereby discharging the marking fluid through the discharge port onto surrounding objects.