The ornamental design for a jug, as shown and described.
FIG. 1 is a front perspective view showing my new design:
FIG. 2 is a top plan view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a rear perspective view thereof.
The broken lines immediately adjacent to shaded areas form the boundaries of the claimed design, all other broken lines show portions of the jug that form no part of the claimed design.