The ornamental design for a desktopholepunch, as shown and described.
FIG. 1 is a front-side perspective view showing our new desktop hole punch with the paper guides in the retracted position, wherein the opposite side of the hole punch is identical to the side shown;
FIG. 2 is a front-side perspective view of the desktop hole punch of FIG. 1 wherein the paper guides are in the extended position;