The ornamental design for a drinkingcup, as shown and described.
FIG. 1 is a perspective view of drinking cup, showing my new design;
FIG. 2 is a right view thereof;
FIG. 3 is a left view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a back view thereof.
The dot dash broken lines in FIGS. 1, 2, 4, and 5 depict both portions of the drinking cup and the boundaries of the claim and form no part of the claimed design. The broken lines and the areas within them depict environmental subject matter that forms no part of the claimed design.