The ornamental design for a toywatergun, as shown and described.
FIG. 1 is a first perspective view of a toy water gun showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
Any broken lines represent boundaries of the claimed design. The areas bound in broken lines and shown in half-tone de-emphasized shading illustrates portions of the toy water gun that form no part of the claimed design. Neither the broken lines themselves nor the de-emphasized areas contained within the broken lines form any part of the claimed design.