The ornamental design of a pajamapants cuff, as shown and described.
FIG. 1 is a front perspective view of a pajama pants cuff showing my new design;
FIG. 2 is a left side view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a front view thereof; and,
FIG. 5 is a back view thereof.
The broken line showing portions of the pajama pants cuff in the figures is included for the purpose of illustrating environmental structure and forms no part of the claimed design.