FIG. 1 is an upper perspective view of the water pistol showing my design.
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is an opposite side view thereof; and,
FIG. 6 is a top view thereof.
I claim the ornamental design for a water pistol, as shown and described.