I claim the ornamental design for a bunk bed, as shown and described.
FIG. 1 is a front corner perspective view of a bunk bed according to an embodiment of the invention. The view from the adjacent front corner being a mirror image thereof.
FIG. 2 is a front elevational view of a bunk bed according to an embodiment of the invention.
FIG. 3 is a right side elevational view of a bunk bed according to an embodiment of the invention.
FIG. 4 is a left side elevational view of a bunk bed according to an embodiment of the invention; and,
FIG. 5 is a top plan view of a bunk bed according to an embodiment of the invention.
The portions of the figures shown in dashed lines are for illustrative purposes only and form no part of the claimed invention. The inside of the end panels are not considered part of the invention.