The ornamental design for an insertablesexualdevice, as shown and described.
FIG. 1 is a top-front-left perspective view of an insertable sexual device showing my new design;
FIG. 2 is a bottom-rear-right perspective view thereof;
FIG. 3 is a front elevational view thereof, the rear elevational view being identical thereof;
FIG. 4 is a left-side elevational view thereof, the right-side elevational view being identical thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines shown in the drawings are for the purpose of illustrating portions of the insertable sexual device, which form no part of the claimed design.