The ornamental design for a massagegun, as shown and described.
FIG. 1 is a perspective view of a massage gun showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear 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;
FIG. 8 is a bottom view thereof; and,
FIG. 9 is an enlarged view of portion 9 shown in FIG. 3.
The broken lines in the drawings depict portions of the massage gun that form no part of the claimed design. The dash-dot broken lines shown in FIGS. 3 and 9 are for the purpose of showing enlarged areas, which form no part of the claimed design.