The ornamental design for a butterstick, as shown and described.
FIG. 1 is an illustration of an isometric view of a first embodiment of a butter stick;
FIG. 2 is an illustration of a top view of the butter stick of FIG. 1 with the bottom view being a mirror image thereof;
FIG. 3 is an illustration of a front view of the butter stick of FIG. 1, with the back view being a mirror image thereof;
FIG. 4 is an illustration of a right side view of the butter stick of FIG. 1, with the left side view being a mirror image thereof;
FIG. 5 is an illustration of an isometric view of a second embodiment of a butter stick;
FIG. 6 is an illustration of a top view of the butter stick of FIG. 5 with the bottom view being a mirror image thereof;
FIG. 7 is an illustration of a front view of the butter stick of FIG. 5, with the back view being a mirror image thereof; and,
FIG. 8 is an illustration of a right side view of the butter stick of FIG. 5, with the left side view being a mirror image thereof.
The evenly-spaced broken lines in FIGS. 1-8 illustrate portions of the butter stick that form no part of the claimed design. The dot-dash broken lines in FIGS. 1, 2, 5 and 6 illustrate the boundary of the claimed design which forms no part thereof. Any portions of the article between the break lines form no part of the claimed design.