The ornamental design for a pettoystick, as shown and described.
FIG. 1 is a top-facing perspective view of the pet toy stick showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side elevational view thereof;
FIG. 5 is a right-side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing of a latch depict environmental structure and form no part of the claimed design. The remaining broken lines depict portions of the pet toy stick and form no part of the claimed design.