The ornamental design for a drinkingmug with writinginstrument, as shown and described.
FIG. 1 is a right side elevation view of a drinking mug with a detachable writing instrument incorporated in the handle of the mug and mug surfaces on which the writing instrument can write, embodying my new design;
FIG. 2 is a front end elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a rear end elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a left front perspective view thereof.
The broken lines depict unclaimed environmental structure.