The ornamental design for a sheettucker, as shown and described.
FIG. 1 is a front perspective view of a sheet tucker of the present invention;
FIG. 2 is a top view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof;
FIG. 7 is an alternative perspective view thereof; and,
FIG. 8 is an environmental perspective view showing the sheet tucker inserted between a mattress covered by a sheet and box spring.
The broken lines shown in the figures are for the purpose of illustrating environment only and form no part of the claimed design. The dashed-dotted lines in FIG. 8 are for the purpose of illustrating an underlying mattress which is covered by a sheet and form no part of the claimed design.