The ornamental design for a can cap, as shown and described.
FIG. 1 is a top left front perspective view of a can cap showing my new design in an closed condition;
FIG. 2 is a top left front perspective view thereof showing the can cap in a partially opened condition;
FIG. 3 is a top left front perspective view thereof showing the can cap in a fully opened condition;
FIG. 4 is a top left front perspective view thereof showing the can cap in a partially opened condition intermediate between that of FIG. 2 and that of FIG. 3;
FIG. 5 is top left rear perspective view thereof showing the can cap in the partially opened condition shown in FIG. 4;
FIG. 6 is an enlarged left side elevational view thereof showing the can cap in a fully opened condition, the right side being a mirror image;
FIG. 7 is an enlarged top left rear perspective view showing the can cap in a partially opened condition similar to FIG. 5; and,
FIG. 8 is bottom right rear perspective view showing the can cap in a substantially fully extended condition.