The ornamental design for a monstertoy, as shown and described.
FIG. 1 is perspective view of a monster toy showing our new design;
FIG. 2 is a front elevation view of the toy of FIG. 1;
FIG. 3 is a rear elevation view of the toy of FIG. 1;
FIG. 4 is a left elevation view of the toy of FIG. 1;
FIG. 5 is a right elevation view of the toy of FIG. 1;
FIG. 6 is a top elevation view of the toy of FIG. 1; and,
FIG. 7 is a bottom elevation view of the toy of FIG. 1.
The broken lines depicted in the drawings show use in an environment only and form no part of the claimed design. The broken lines on the overalls of the monster toy depict stitching.