The ornamental design for a sign, as shown and described.
FIG. 1 is a front plan view of the sign of the present invention according to a first embodiment;
FIG. 2 is an enlarged perspective view of the sign of FIG. 1;
FIG. 3 is a front plan view of the sign of the present invention according to a second embodiment;
FIG. 4 is an enlarged perspective view of the sign of FIG. 3;
FIG. 5 is a front plan view of the sign of the present invention according to a third embodiment;
FIG. 6 is an enlarged perspective view of the sign of FIG. 5;
FIG. 7 is a front plan view of the sign of the present invention according to a fourth embodiment;
FIG. 8 is an enlarged perspective view of the sign of FIG. 7;
FIG. 9 is a front plan view of the sign of the present invention according to a fifth embodiment; and,
FIG. 10 is an enlarged perspective view of the sign of FIG. 9.
A back view of the sign illustrated in the figures is not provided as it does not form part of the claimed design. In the drawings, the broken lines represent environmental structure forming no part of the claim.