I claim an ornamental design for a weighted sleeve for a floating cup, as shown and described.
FIG. 1 is a perspective view of the weighted sleeve for a floating cup.
FIG. 2 is a front elevational view of the weighted sleeve for a floating cup (the left side view, the right side view and rear view being identical to the front elevational view).
FIG. 3 is a top view of the weighted sleeve for a floating cup; and,
FIG. 4 is a bottom view of the weighted sleeve for a floating cup.
In the drawings, the broken lines illustrate the environment and form no part of the claimed design. In the drawings, the stippling illustrates a contrasting color or material.