The ornamental design for a sign, as shown and described.
FIG. 1 is a right side elevational view of a first embodiment of a sign;
FIG. 2 is a front elevational view thereof, the rear elevational view being a mirror image of the front elevational view shown;
FIG. 3 is a front, top, and right side perspective view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a right side elevational view of a second embodiment of a sign;
FIG. 6 is a front elevational view thereof, the rear elevational view being a mirror image of the front elevational view shown;
FIG. 7 is a front, top, and right side perspective view thereof; and,
FIG. 8 is a top plan view thereof.
To the extent that the bottom view in the first and second embodiments of the sign is not seen in FIGS. 1-8, the bottom view of each of the first and second embodiments is disclaimed and thus does not limit the claimed design.