The ornamental design for a guthook substantially, as shown and described.
FIG. 1 is a perspective view of a gut hook, showing my new design.
FIG. 2 is a rear elevational view thereof.
FIG. 3 is a right side elevational view thereof.
FIG. 4 is a front elevational view thereof.
FIG. 5 is a left side elevational view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
Stippling and shading lines shown in the drawings are intended to represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration. The broken lines in the figures are for illustrative purposes only and form no part of the claimed design.