The ornamental design for a slingbag, as shown and described.
FIG. 1 is a perspective view of a first embodiment of the sling bag;
FIG. 2 is a front view of the first embodiment of the sling bag;
FIG. 3 is a rear view of the first embodiment of the sling bag;
FIG. 4 is a right side view of the first embodiment of the sling bag;
FIG. 5 is a left side view of the first embodiment of the sling bag;
FIG. 6 is a top view of the first embodiment of the sling bag; and,
FIG. 7 is a bottom view of the sling bag.
The broken lines showing in the figures are included for the purpose of illustrating portions of the sling bag that form no part of the claimed design. The dash-dot lines showing in the figures are included for defining the bounds of the claimed design that form no part therof.