The ornamental design of a narwhalcupholder, as shown and described.
FIG. 1 is a rear perspective view of the narwhal cup holder.
FIG. 2 is a front view of the narwhal cup holder.
FIG. 3 is a rear view of the narwhal cup holder.
FIG. 4 is a left-side view of the narwhal cup holder.
FIG. 5 is a top view of the narwhal cup holder; and,
FIG. 6 is a bottom view of the narwhal cup holder.
The design features a narwhal-shaped cup holder, where the cup holder portion exists on the narwhal's back. The broken lines form no part of the claimed design.