The ornamental design of a mononeckpacifier, as shown and described.
FIG. 1 is a top, front, right side perspective view of the mono neck pacifier showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view, the rear view being a mirror image thereof;
FIG. 4 is a right side elevational view, the left side being a mirror image thereof; and,
FIG. 5 is a bottom plan view thereof.
The broken lines showing structural features are included for the purpose of illustrating non-claimed subject matter and form no part of the claimed design.