The ornamental design for a sign, as shown and described.
FIG. 1 is a top, left, front perspective view of a sign showing our new
design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a left side elevational view thereof, the right, front, and rear
sides being identical; and,
FIG. 4 is a bottom plan view thereof.
The subject matter shown in broken line represents unclaimed environmental
structure which is shown for illustrative purposes and forms no part of
the claimed design.